Mathieu Tillier

LOCAL TRADITION AND IMPERIAL LEGAL POLICY UNDER THE UMAYYADS: THE EVOLUTION OF THE EARLY EGYPTIAN SCHOOL OF LAW

Keywords: Egypt, Umayyads, legal schools, madhhabs, jurists, fiqh, judiciary, qadis economic, political and military interactions

Joseph Schacht considered that Egypt did not develop any original school of law during the second/eighth century, and that its early jurists followed the Medinan tradition. However, in the early Abbasid period, Egyptian jurist al-Layth b. Saʿd supported an autonomous Egyptian legal tradition, based on the jurisprudence of the Companions who had taken part in the conquest. This suggests that Egypt followed an original legal tradition during the Umayyad and the early Abbasid periods, a tradition that was challenged, then replaced, by other schools in the first half of the ninth century CE. In order to understand the peculiarities and evolution of this Egyptian legal tradition, this article propose a preliminary study of the relationships between Egyptian jurists and other regional normative systems within the Islamic empire. I argue that the evolution of the Egyptian "school" is related to imperial Umayyad policy, especially to the legal agenda of Caliph ʿUmar b. ʿAbd al-ʿAzīz.

the Umayyad and the early Abbasid periods, a tradition that was challenged, then replaced, by other schools-most significantly those of Mālik, then al-Shāfiʿī, in the first half of the third/ninth century.

Our lack of knowledge of jurisprudence in Umayyad Egypt is partly due to historiographical reconstructions that took place during the Abbasid period. Perhaps because Egypt quickly adhered to "personal" schools of law related to the Medinan tradition (Mālikism and Shāfiʿism), most legal sources leave no room for Egyptian jurists before al-Layth b. Saʿd. We therefore ignore most early Egyptian legal doctrines and practices. 4 However, a close reading of a fourth/tenth-century text allows us to lift a corner of the veil that conceals the Umayyad history of the Egyptian legal milieu. The historian Ibn Yūnus al-Ṣadafī al-Miṣrī (d. 347/958) wrote a biographical work about the most important Egyptian figures of the early Islamic centuries. The book itself has disappeared, but many quotes preserved by later authors allowed ʿAbd al-Fattāḥ Fatḥī ʿAbd al-Fattāḥ to propose a hypothetical reconstruction that is the main basis for the present study. 5 Moreover, Ibn Yūnus's contemporary, Abū ʿUmar al-Kindī (d. c. 350/961), wrote a History of Egyptian Judges, opening a window onto Fusṭāṭ's legal and judicial circles. 6 To understand the peculiarities of the Egyptian legal circles during the Umayyad period, I will first offer a preliminary study of the relationships between its local jurists and other regional normative systems within the Islamic empire. Second, I will argue that the evolution of the Egyptian "school" is intimately related to imperial Umayyad policy.

Egyptian Law under the Umayyads, between Theory and Practice

The Early Egyptian Legal Milieu

A few mentions of faqīhs or muftīs by Ibn Yūnus attest to the existence of an early Islamic Egyptian legal milieu. Several characters who settled in Fusṭāṭ following the conquest reportedly transmitted ḥadīth from important Companions of the Prophet, such as ʿUmar b. alsame semantic field of the normative "path" as sharīʿa. The term came to designate the "path", the "trend" followed by a series of jurists, characterized by their adhesion to a common tradition in spite of their individual differences. The expression "schools of law" to refer to pre-classical legal trends, as well as their regional nature, has been the subject of controversy over the past two decades, involving particularly Nimrod Hurvitz ("Schools of Law and Historical Context: Re-Examining the Formation of the Ḥanbalī Madhhab," Islamic Law and Society 7 (2000), 37-64), Wael Hallaq ("From Regional to Personal Schools of Law? A Reevaluation," Islamic Law and Society 8 (2001), 1-26) and Christopher Melchert ("Traditionist-Jurisprudents and the Framing of Islamic Law," Islamic Law and Society 8 (2001), 400). See also S.C. Judd, "Al-Awzāʿī and Sufyān al-Thawrī: The Umayyad Madhhab?" in The Islamic School of Law: Evolution, Devolution, and Progress, ed. P. Bearman, R. Peters and F.E. Vogel (Cambridge: Harvard University Press, 2005), 13, in which the author argues that some jurists' mobility makes it difficult to attach them to any region. My own conclusion is that regional trends indeed existed in the eighth century CE. See M. Tillier, Les cadis d'Iraq et l'État Abbasside (132/750-334/945) (Damascus: Ifpo, 2009), 138-143. 4 J.E. Brockopp, one of the rare scholars who wrote about the formation of an Egyptian school, only devotes two pages to its history before 775 C.E. He mainly highlights the role of Alexandria as a place of transmission of knowledge during the early period. J.E. Brockopp, "The Formation of Islamic Law: The Egyptian School (750-900)," Annales Islamologiques 45 (2011), 130-1. 5 Ibn Yūnus, Taʾrīkh Ibn Yūnus al-Miṣrī, ed. ʿAbd al-Fattāḥ Fatḥī ʿAbd al-Fattāḥ (2 vols., Beirut: Dār al-kutub al-ʿilmiyya, 2000). 6 Al-Kindī, Akhbār quḍāt Miṣr, in The Governors and Judges of Egypt, ed. R. Guest (Leiden, Brill, 1912), 299-476; French translation by M. Tillier in al-Kindī, Histoire des cadis égyptiens (Cairo: IFAO, 2012). Khaṭṭāb,Muʿādh b. Jabal,and Umm Salama. 7 According to Ibn Yūnus, caliph ʿUmar ordered ʿAmr b. al-ʿĀṣ, the conqueror and first governor of the province, to move ʿAbd al-Raḥmān b. Muljam's house closer to the mosque, so that he could teach the Qur'an and fiqh there. 8 Qays b. al-Ḥārith al-Murādī, who arrived from Yemen during the conquest, similarly "learnt fiqh (tafaqqaha) so that he could give legal opinions in his time (yuftī fī zamāni-hi)." 9 It is unclear if the term fiqh was actually used at that time. Qays b. al-Ḥārith's example suggests, however, that such people were recognised as the bearers of a special kind of knowledge that allowed them to provide some sort of legal or religious advice.

The Egyptian tradition, however, assigns a substantial role in the formation of a legal milieu to a particular Companion: ʿUqba b. ʿĀmir (d. 58/677-8). He is best known for having participated in the conquest of Egypt, and became its governor from 44/665 to 47/667, under the caliph Muʿāwiya. 10 Ibn Yūnus considers ʿUqba b. ʿĀmir a leading expert in law and the author of a local recension of the Qur'an, which remained authoritative in Egypt for some time, perhaps until c. 76/695-6, when governor ʿAbd al-ʿAzīz b. Marwān (r. 65-86/685-705) ordered to write down a new codex. 11 Among the early jurists that Ibn Yūnus identifies, ʿUqba b. ʿĀmir is the only one who supposedly reported directly from the Prophet, which may have given him a special authority. Indeed, al-Dhahabī later refers to him as "the Imām." 12 He apparently played an important role in training the second generation of Egyptian jurists. Among others, he taught Marthad b. ʿAbd Allāh al-Yazanī (d. 90/709), who became a close adviser of the governor ʿAbd al-ʿAzīz b. Marwān at the turn of the second/eighth century, and issued "fatwas" during official hearings. 13 islāmī, 1991), 4:62-9; L. Veccia Vaglieri, "Ibn Muldjam," EI 2 , s.v. 9 Ibn Yūnus, Taʾrīkh, 1:401. 10 Al-Kindī, Taʾrīkh Miṣr wa-wulāti-hā, in The Governors and Judges of Egypt, ed. R. Guest (Leiden: Brill, 1912), 36-38;Ibn Yūnus, Taʾrīkh, 1:347;al-Suyūṭī, Ḥusn al-muḥāḍara fī taʾrīkh Miṣr wa-l-Qāhira, ed. Muḥammad Abū l-Faḍl Ibrāhīm (2 vols., Cairo: Dār iḥyāʾ al-kutub al-ʿarabiyya/ʿĪsā al-Bābī al-Ḥalabī, 1967), 1:220. On ʿUqba b. ʿĀmir, see also Ibn Saʿd, Kitāb al-ṭabaqāt al-kabīr, ed. ʿAlī Muḥammad ʿUmar (11 vols., Cairo: Maktabat al-Khānjī, 2001), 5:261; Khalīfa b. Khayyāṭ, Kitāb al-ṭabaqāt, ed. Suhayl Zakkār (Beirut: Dār al-fikr, 1993) Khoury, ʿAbd Allāh Ibn Lahīʿa (97-174/715-790): Juge et grand maître de l'école égyptienne (Wiesbaden: Otto Harrassowitz, 1986), 96-7;Khayr al-Dīn al-Ziriklī, al-Aʿlām: Qāmūs tarājim li-ashhar al-rijāl wa-l-nisāʾ min al-ʿarab wa-l-mustaʿribīn wa-l-mustashriqīn, 12th ed. (8 vols., Beirut: Dār al-ʿilm li-l-malāyīn, 1997), 4:240. 11 Ibn ʿAbd al-Hakam, Futūḥ Miṣr, 117-8. Cf. Ibn Duqmāq, al-Juz' al-rābiʿ min Kitāb al-intiṣār (Cairo: al-Maṭbaʿa al-kubrā al-amīriyya, 1309 H.), 72-3; al-Maqrīzī, al-Mawāʿiẓ wa-l-iʿtibār bi-dhikr al-khiṭaṭ wa-l-āthār, ed. Ayman Fuʾād Sayyid (5 vols., London: Muʾassasat al-furqān li-l-turāth al-islāmī, 2002-2003), 4/1:30-1; Ibn Ḥajar al-ʿAsqalānī, Rafʿ al-iṣr ʿan quḍāt Miṣr, ed. ʿAlī Muḥammad ʿUmar (Cairo: Maktabat al-Khānjī, 1998), 215. 12 Ibn Yūnus,Taʾrīkh,1:468;Futūḥ Miṣr, Ibn Yūnus, Taʾrīkh, 1:347, 468; al-Dhahabī, Siyar aʿlām al-nubalāʾ (ed. Shuʿayb al-Arnaʾūṭ and Muḥammad Nuʿaym al-ʿAraqsūsī. 23 vols., Beirut: Muʾassasat al-risāla, 1413 H.), 4:285. 14 Ibn Yūnus, Taʾrīkh, 1:298-9. On this character, see Khoury, ʿAbd Allāh ibn Lahīʿa, 99. According to al-Kindī, qadi ʿĀbis b. Saʿīd (in office from 60 to 68/679-80 to 687-8) also owed his legal training to ʿUqba b. ʿĀmir. 15 These few names reveal the existence, in the last quarter of the seventh century, of a small group of jurists surrounding the governor, rooted in the local community of Fusṭāṭ. They followed the legal expertise of ʿUqba b. ʿĀmir, one of the first governors serving the Sufyānid caliphate, whose knowledge and recension of the Qur'an were authoritative. 16 This Egyptian tradition continued into the second/eighth century. Ibn Yūnus' biographies of jurists are not detailed enough to precisely reconstruct the legal circles that developed from the first/seventh-century kernel. However, he provides some information about transmission of ḥadīth, following the trend of the biographical literature of his time. What ḥadīth was at the turn of the second/eighth century is also unclear, and such information is probably reconstructed from isnāds-the authenticity of which may be questioned. Even if one might suspect a later reconstitution of the isnāds as part of the process of creating formal ḥadīths, they could only appear credible if they followed historically realistic lines of transmission. This suggests that these transmission channels may reflect some historical transfers of knowledge and contacts between Egyptian scholars. Taken as such, Ibn Yūnus' text shows that until the first two decades of the eighth century C.E., an Egyptian tradition mainly rooted in the teaching of the Companions who settled in Fusṭāṭ (ʿUqba b. ʿĀmir, ʿAmr b. al-ʿĀṣ, and his son ʿAbd Allāh b. ʿAmr) and their Egyptian followers continued. This legal tradition, whose main representatives are ʿAbd al-Raḥmān b. Jubayr and Bakr b. Sawāda (d. 128/745-6),17 reached its climax with al-Layth b. Saʿd, who appeared as the main representative of the Egyptian "school" of law in the second half of the second/eighth century. 18 Al-Layth b. Saʿd clearly refers to this milieu in his letter to Mālik, when he insists on the local origin of the legal traditions he upholds, arguing that they go back to the teaching of Companions who settled in Fusṭāṭ after the conquest. 19 This local legal current apparently grew weaker during the second half of the second/eighth century, when Mālik's teaching gradually replaced it. 20 Al-Layth b. Saʿd was probably one of the last defenders of this local Egyptian tradition. His legal doctrine continued to be distinguished from that of Mālik. In the early fourth/tenth century, the Ḥanafī Egyptian jurist al-Ṭaḥāwī (d. 321/933) still regularly cites him in his book, A Concise Treaty of Disagreements Among Jurists (Mukhtaṣar ikhtilāf al-ʿulamāʾ), alongside the main representatives of other early regional "schools," such as Ibn Abī Laylā (d. 148/765) and Sufyān al-Thawrī (d. 161/778) in Kūfa. In his opinion, al-Layth b. Saʿd still represented an important "school"although it had disappeared in his time and non-Egyptian jurists did not bother to mention it.

Were Egyptian Jurists Isolated?

This local legal "school," mostly visible in the last quarter of the first/seventh century and the early second/eighth century, was progressively replaced under the Abbasids by the personal schools of Mālik b. Anas, then of al-Shāfiʿī (if we follow Schacht's classification). This suggests that somewhere in the Marwānid period, external legal circles, especially from Medina, to whose legal tradition Mālik belonged, influenced Egypt. We need therefore to examine the integration of Egyptian jurists in the legal effervescence that characterized other provinces (especially the Hijaz, Iraq, and Syria) in the first half of the second/eighth century.

A First Approach: Citations of Egyptian Jurists in Early Ninth-century Muṣannafs

The best witnesses to this busy legal activity come from the first collections of traditions sorted by legal categories. The Muṣannafs of ʿAbd al-Razzāq al-Ṣanʿānī (d. 211/827) and Ibn Abī Shayba (d. 235/849) offer an exceptional image of regional legal divergences during the Umayyad period. These two ancient tradition collections report almost systematically the opinions and sayings attributed to the early jurists of Kūfa (such as Ibn Shubruma and Ibn Abī Laylā), Baṣra (like Ibn Sīrīn), Medina, Mecca, and Syria (Makḥūl). These books thus reveal what their two authors, a Yemeni and an Iraqi, knew at the beginning of the third/ninth century about legal disagreements in Marwānid times. A systematic search for citations of Egyptian jurists identified as such by Ibn Yūnus in both Muṣannafs allows us to assess the degree to which the Egyptian legal school of the Umayyad period was known outside Egypt a few decades later: 21 ----------------------------------------------------------------------- -21 The following assessment is based on a count in the electronic versions of both works in the database al-Maktaba al-shāmila, version 3.48 (http://shamela.ws/). I added ʿAbd Allāh b. Lahīʿa to the list, although he does not appear as a faqīh in Ibn Yūnus' work, for the sake of comparison. Ibn Lahīʿa appears indeed to be one of the most important second/eighth century Egyptian scholars. 22 It is possible to add to this figure the four occurrences of the phrase ʿan al-Layth, although we cannot ascertain that it refers to al-Layth b. Saʿd. At any rate, they do not introduce any opinion attributed to the Egyptian master.

Egyptian jurists Citations in both Muṣannafs

Total 158

In most instances, these Egyptian jurists appear in chains of transmitters, and their own legal opinions are not quoted. ---------------------------------------------------Total 3503

These figures suggest that Egyptian jurists from the Umayyad and the early Abbasid periods were poorly known in Iraq and Arabia in the early third/ninth century. Even al-Layth b. Saʿd, although he is considered the most important Egyptian jurist of the early Abbasid period, is totally neglected by Ibn Abī Shayba, and he is not even mentioned by ʿAbd al-Razzāq. How can we interpret such ignorance of Egyptian legal tradition?

The most likely answer is that these Egyptian jurists were only known locally, and had minimal interactions with jurists from other provinces. The major late eighth-century legal debates involved mainly Iraqis and Medinans. Syrian jurists were rapidly marginalized, but their opinions left important traces, mainly in the teaching of al-Awzāʿī (d. 157/774). As for the Egyptians, most Eastern jurists perhaps did not even know of them. Such lack of mutual awareness between local and non-Egyptian scholarship is confirmed in Egypt's first ḥadīth works. In the earliest known Egyptian collection, the papyrus scroll of ʿAbd Allāh b. Lahīʿa (d. 174/790) (probably early ninth century), almost all the transmitters that can be identified lived in Egypt. [START_REF] Khoury | ʿAbd Allāh ibn Lahīʿa[END_REF] The Jāmiʿ of Ibn Wahb (d. 197/812) could apparently contradict this conclusion, for the author cites Iraqi and Medinan/Yemeni scholars from the Umayyad period. [START_REF]As for Iraqi jurists, he cites for example, Muḥammad b. Sīrīn (Ibn Wahb[END_REF] It is worth remembering, however, that Ibn Wahb travelled to Medina where he closely followed Mālik's teaching, before returning to Egypt. [START_REF] David-Weill | Ibn Wahb[END_REF] A close attention to isnāds reveals furthermore that the Umayyad-period transmitters were not Egyptians. Egyptian transmitters only occur in the Abbasid period, which suggests that they learned these traditions from Eastern scholars with whom they interacted after the revolution. 26

A Prosopographical Approach: Lists of Masters and Disciples

Other data provided by Ibn Yūnus point to the few interactions between Egyptians and other jurists. In his (reconstructed) volume dedicated to "foreigners" (ghurabāʾ) who spent time in Egypt, only rare scholars belonging to the Umayyad period are labelled as faqīh. The main one is ʿUrwa b. al-Zubayr (d. 93/711-12?), one of the "seven jurists" of Medina, who may have spent seven years in Fusṭāṭ. 27 However, Gregor Schoeler has doubts regarding the reliability of this information, which is also transmitted by al-Balādhurī. [START_REF]These three names occur in al-Dhahabī[END_REF] Among the few others are a jurist from Ifrīqiya and the Khārijī Imām Abū l-Khaṭṭāb (d. 144/761), who stopped in Fusṭāṭ on his way to central Maghreb at the beginning of the Abbasid period. 29 However, the data provided by Ibn Yūnus are certainly incomplete, and we can assume that other legally trained "foreigners" travelled to Fusṭāṭ, notwithstanding the fact that Egyptian jurists may have travelled to other regions of the empire. It is therefore necessary to examine more carefully biographical data available for Egyptian jurists.

Ibn Yūnus gives short lists of teachers and disciples for each of these jurists. Later authors, such as al-Dhahabī (d. 748/1348) and al-Suyūṭī (d. 911/1505), offer more exhaustive lists. These later lists raise an even more delicate problem of interpretation than that of Ibn Yūnus, as they were probably drawn up on the basis of a systematic census of names appearing in isnāds. They reflect above all the transmission channels of ḥadīth, and not the teaching of fiqh itself. Here again, we consider these lists as reflecting plausible interactions between scholars during the Umayyad period. In order to better understand the image of such interactions, we have identified the masters and disciples of jurists categorized as such by Ibn Yūnus, adding to his short lists the data provided by al-Dhahabī and al-Suyūṭī, and classified these masters and disciples by 25 year increments according to the province with which they are most associated. [START_REF]The last four names are given by al-Dhahabī, Taʾrīkh al-islām, 3:562. Name Date of death Reference in Ibn Yūnus Learned from Taught[END_REF] We consider here the number of teachers and disciples in absolute value: if the same master/disciple is repeated several times in the same period, we count these repetitions. Dhahabī, Taʾrīkh al-islām, ed. Bashshār ʿAwwād Maʿrūf (15 vols., Beirut: Dār al-gharb al-islāmī, 2003), 4:179) (Ibn Wahb, Jāmiʿ, 1:185). 27 Ibn Yūnus, Taʾrīkh, 2:147. [START_REF]These three names occur in al-Dhahabī[END_REF] G. Schoeler, "ʿUrwa b. al-Zubayr," EI 2 , 10:983. 29 Ibn Yūnus, Taʾrīkh, 2:109. [START_REF]The last four names are given by al-Dhahabī, Taʾrīkh al-islām, 3:562. Name Date of death Reference in Ibn Yūnus Learned from Taught[END_REF] The last period (801-816) has only 15 years, however, and the corresponding parts of graphs 1 and 2 must therefore be corrected upwards.

According to these sources, we should note first that hardly any Egyptian jurist who died before 725 had a master from the east of the empire (Graph. 1). The only "masters" outside Egypt come from the Hijaz (i.e., here, Medina). These are more numerous than Egyptian masters, for the good reason that they were Companions of the Prophet, whom our Egyptian jurists probably met before they settled in Egypt. Up until that date, interactions with non-Egyptian disciples appear almost non-existent (Graph. 2).

The data available regarding jurists active at the end of the Umayyad period suggest at first sight that there was a strong influx of Hijazi masters (Graph. 1). However, it should be noted that, among the 12 Hijazi masters of jurists who died between 726 and 750, 11 taught a single person, Yazīd b. Abī Ḥabīb, to whom we will return in more detail. With the exception of this jurist, the number of Egyptian masters remained much higher than those from other provinces. Similarly, these jurists' disciples were still predominantly Egyptians (Graph. 2). Very few Hijazis and Iraqis seem to have studied with them. However, a significantly higher It was not until the generation of jurists who died in the last quarter of the second/eighth century that a shift occurred. A majority of masters belonging to this generation were still Egyptians; however, they were now closely competing with the Hijazis, a phenomenon that seems to continue after the year 800 (Graph. 1). These Egyptian jurists, active in the second half of the second/eighth century, transmitted the teaching they received from the great Hijazi masters of the first half of the second/eighth century or the first two decades of the Abbasid period (Graph. 3). At the same time, the geographic origin of their disciples was diversifying, with an increasing number of scholars associated with the eastern part of the empire, particularly Khurasan. Nevertheless, the majority of these jurists' students were still Egyptians (Graph. 2).

These prosopographical data thus provide also an image of a fairly closed Egyptian legal milieu during most of the Umayyad period. With the exception of Yazīd b. Abī Ḥabīb, Egyptian jurists of the period had almost no master from outside their province and, with the exception of a few Ifrīqians, they trained only a very limited number of disciples who then moved to another part of the empire. Nevertheless, according to late prosopographical data, Hijazi masters were not unknown in Egypt: Egyptian jurists active in the second half of the second/eighth century seem to have often studied with them (among others) when they were young, which had a strong impact on the diffusion of Medinan knowledge in Egypt during the early decades of the Abbasid period. However, these data should be taken with caution: the rise in authority of Medinan scholars in the early Abbasid era, in connection with the emergence of a proto-Mālikī school, might have led some Egyptians to claim that they had studied with Hijazi masters whom they had actually never met, or encouraged the invention of isnāds going back to them. Examining the role of Fusṭāṭ's qadis in transmitting ḥadīth, Gauthier Juynboll concludes that "the requirements for the office were not high," meaning that most had limited legal skills. 31 Moreover, Ibn Yūnus includes no Umayyad-era qadi from Fusṭāṭ on his list of qualified Egyptians faqīhs. Expertise in fiqh was probably not the most important criterion in selecting Fusṭāṭ's judges. The latter usually belonged to the major Arab tribes of Fusṭāṭ, which suggests that their status as members of the ruling elite was regarded as the most important condition.

Egyptian Legal Practices Compared to Other Regional Procedures

On the other hand, 22 out of the 37 Egyptian jurists that Ibn Yūnus identifies in his book were mawālī (more than 59 percent), and could not reasonably expect to be appointed as qadi-their judicial career was limited to the role of scribe. 32 This does not necessarily mean that Fusṭāṭ's judges had no legal training, or that they were detached from the legal thought developed in their province. It is therefore necessary to consider how court procedure in Fusṭāṭ can be correlated with those in other provinces.

Procedural law was the subject of debates between "Eastern" jurists (especially Iraqi and Medinan ones) in the first half of the eighth century. A comparison between Egyptian and Eastern judicial practices may therefore represent a significant indicator of the legal integration of Egypt into the Umayyad empire. Information al-Kindī provides allows comparisons with major Middle-Eastern cities:

Procedures in Fusṭāṭ

Medina Baṣra Kūfa Damascus The litigant who produces the higher number of witnesses wins the lawsuit 33 (69-83/688-89-702)

X 34 X 35 X 36
The judge draws lots when litigants produce the same number of witnesses 37 (69-83/688-89-702)

X 38 Evidence based on one single witness + the claimant's oath 39 (115-120/733-738) X 40 X 41 X 42

The testimony of ashrāf is rejected [START_REF] Al-Quḍāt | [END_REF] (115-120/733-738)

A man who denied his divorced wife a compensatory gift cannot testify44 (115-120/733-738)

The testimony of children is accepted in case of injury45 (120-127/738-745) X 46 X 47 X [START_REF] Al-Ṣanʿānī | [END_REF] The testimony of a litigant's brother is accepted 49 (120-127/738-745) X 50 X 51 X 52 No 53 A Christian may testify against a Christian, a Jew against a Jew 54 (120-127/738-745) X 55 X 56 Except for two cases of witness disqualification that seem specific to Egypt, without any equivalent in other provinces, the same basic rules regarding testimony, and probably oaths as well, were simultaneously implemented in other parts of the empire. According to the table above, judicial practices in Fusṭāṭ came closest to Medinan standards. An archaic procedure of judging in favor of the litigant who produced the higher number of witnesses was also accepted in Damascus and Baṣra. After Medina, Fusṭāṭ shared several particular rules with Baṣra, and to a lesser extent, with judges in Kūfa towards the end of the Umayyad period. These indications raise a question regarding our previous conclusions about Fusṭāṭ's isolation from the rest of the empire. Judicial practices in Umayyad Fusṭāṭ match those of other provinces. It remains to determine how such similarities came about. Are these parallel developments unrelated to each other, from a common background dating back to the early decades of Islam and for which we have virtually no information? Alternatively, can we argue that these judicial practices developed simultaneously, due to other types of interaction between provinces?

Several clues suggest that Egyptian judicial practices resulted from interactions with other provincial traditions. 57 The procedure al-yamīn maʿa al-shāhid (evidence constituted of a single witness plus the claimant's oath) was used in Fusṭāṭ during the last decade of Umayyad rule. In his letter to Mālik b. Anas, al-Layth b. Saʿd rejected this procedure, arguing that it had a Medinan origin, while Egypt had its own tradition, inherited from the Companions who settled in Fusṭāṭ. [START_REF]The last three names are given by al-Dhahabī[END_REF] A passage from al-Kindī confirms that the emerging authority of Medinan practice was not accepted in Fusṭāṭ without assessing its adequacy to local traditions. In the early Abbasid period, the qadi ʿAbd Allāh b. Lahīʿa reported that the Medinan jurist, Ibn al-Shihāb Zuhrī (d. 124/742), accepted the testimony of a single witness, provided that he also transmitted the statement of a second (absent) witness. According to Ibn Lahīʿa, this opinion was consistent with the practice of most Umayyad period Egyptian qadis. [START_REF] Yūnus | -Suyūṭī[END_REF] Ibn Lahīʿa had heard it from the Egyptian traditionist Yazīd b. Abī Habīb (d. 128/745-6), which suggests that al-Zuhrī's opinions were known in Egypt during the Umayyad period. However, it remains unclear whether the practice of Egyptian qadis matched al-Zuhrī's views because they regarded him as authoritative or for other reasons. Ibn Lahīʿa declares that he agrees with al-Zuhrī, not through blind adhesion to his views, but according to his own personal reflection (raʾy): he claims thereby the doctrinal independence of Egyptian jurists. The harmony between Egyptian practices and Medinan theory seems therefore to have been partly reconstructed-or at least rationalized-during the early Abbasid period, when Egyptian scholars such as al-Layth b. Saʿd and Ibn Lahīʿa began to compare Egyptian customs with the doctrines of the major legal centers whose influence was growing throughout the empire. The similarity of practices between Egypt and Medina during the Umayyad period were not seen as the voluntary adoption of foreign doctrines, but rather as a happy coincidence.

Egypt's Integration into an Imperial Legal Framework

The picture to this point is of a fairly isolated Umayyad Egypt in terms of interactions between jurists. However, similarities between Egyptian judicial practices and those of other provinces, especially the Hijaz, offer a contrasting view. Egyptian jurists, anxious to preserve their local traditions, later considered this harmony a happy coincidence. But can we believe in coincidences? If interactions between Umayyad jurists fail to explain such parallel practices, should we not consider other protagonists?

Al-Layth b. Saʿd's letter to Mālik b. Anas offers a clue, namely that imperial policy may be responsible for such common judicial practices. Al-Layth considers Caliph ʿUmar II b. ʿAbd al-ʿAzīz (r. 99-101/717-720) as the promoter of double testimony instead of "archaic" types of 57 See for example, al-Kindī, Akhbār quḍāt Miṣr, 350-1. [START_REF]The last three names are given by al-Dhahabī[END_REF] Yaḥyā b. Maʿīn, Taʾrīkh, 4:491; al-Fasawī, Kitāb al-maʿrifa wa-l-taʾrīkh, 1:691; Ibn Qayyim al-Jawziyya, Iʿlām al-muwaqqiʿīn ʿan rabb al-ʿālamīn (5 vols., Beirut: Dār al-kutub al-ʿilmiyya, 1991), 3:71. Christopher Melchert believes that this procedure appeared in Baṣra, and that its Medinan origin is but a rear projection ("The History of the Judicial Oath in Islamic Law," in Oralité et lien social au Moyen Âge (Occident, Byzance, Islam): parole donnée, foi jurée, serment, ed. Marie-France Auzépy and Guillaume Saint-Guillain (Paris: ACHCByz, 2008), 325). However he does not take into account reports claiming that early Medinan qadis had recourse to this procedure. [START_REF] Yūnus | -Suyūṭī[END_REF] Al-Kindī, Akhbār quḍāt Miṣr, 346. evidence that had existed in Egypt, such as isolated testimony or higher number of witnesses. [START_REF]The last two names are given by al-Dhahabī[END_REF] In the context of his controversy with Mālik, al-Layth's insistence on ʿUmar II is part of his argumentative strategy, which consists to appeal to an authority that Mālik himself acknowledges. It must therefore be taken with a grain of salt. Nevertheless, one cannot overlook the possibility that Umayyad rulers played an important role in rationalizing legal procedures, and more broadly in the development of Egyptian law.

Official Instructions

Legal and narrative sources highlight the importance of political relationships between Egypt and the capital of the empire during the Umayyad period. Since the reign of ʿAbd Allāh b. al-Zubayr (r. 63-73/683-692) and that of his rival and successor, ʿAbd al-Malik b. Marwān (r. 65-86/685-705), caliphs sent legal instructions and judicial rescripts to provincial qadis, governors and other officials. [START_REF] Schacht | Ibn al-Ḳāsim[END_REF] In Egypt, correspondence between caliphs and governors is mostly known from the reigns of ʿUmar b. ʿAbd al-ʿAzīz and Hishām b. ʿAbd al-Malik (r. 105-125/724-743), who reportedly sent instructions to the qadis of Fusṭāṭ, directly or through the provincial governor. As in other cities of the empire, qadis and governors were sometimes caught off guard by legal cases brought to court and solicited therefore the caliph's instructions, who then enacted general rules and prescribed implementing specific procedures. 62 The latter married a woman. The day of the consummation of the marriage, she was wearing a long coat (milḥafa). He undressed her and suddenly noticed a leprosy scar on her lower thigh.

"Put your coat back on!" he ordered. He spoke to ʿAbd Allāh b. Yazīd b. Khudhāmir, who wrote to ʿUmar b. ʿAbd al-ʿAzīz on his behalf. The latter replied: "Let him take an oath before God, in the mosque, that he did not touch her after seeing [the scar]. And let her brothers swear that they were unaware of her illness before they gave her in marriage. If they take the oath, assign a quarter of the dowry (ṣadāq) to the wife." 63 60 Yaḥyā b. Maʿīn, Taʾrīkh, 4:491; al-Fasawī, Kitāb al-maʿrifa wa-l-taʾrīkh, 1:691-2; Ibn Qayyim al-Jawziyya, Iʿlām al-muwaqqiʿīn, 3:71-2. [START_REF] Schacht | Ibn al-Ḳāsim[END_REF] See M. Tillier, "Califes, émirs et cadis: le droit califal et l'articulation de l'autorité judiciaire à l'époque umayyade," Bulletin d'Études Orientales 63 (2014), 161-165, 172-175. 62 See Tillier, "Califes, émirs et cadis." Ibn Saʿd and al-Balādhurī's biographies of ʿUmar II report dozens of caliphal rescripts sent to different governors of the empire regarding legal and procedural rules. See esp. Ibn Saʿd, Kitāb al-ṭabaqāt al-kabīr, 7:350, 357, 365, 366, 370, 371, 374, 381;al-Balādhurī, Ansāb al-ashrāf, ed.Suhayl Zakkār and Riyāḍ Ziriklī (13 vols., Beirut: Dār al-fikr, 1996), 8:138, 148, 150, 155-8, 162, 163, 165, 166, 184, 189, 195. 63 Al-Kindī, Akhbār quḍāt Miṣr, 338-9.

Such rescripts contributed to disseminating caliphal law in Fusṭāṭ, in the sense of legal rulings decided by the caliph, whatever the sources on which his decisions were based. Although Egyptian qadis usually relied on provincial legal traditions, they periodically sought caliphal instructions, which helped integrate their judicial practices into an empire-wide legal framework.

Imperial Legal Policy

According to the sources, a turning point for the integration of Egyptian law into an imperial legal framework occurred around the year 720 C.E., during the reign of Caliph ʿUmar II b. ʿAbd al-ʿAzīz. His legal edicts and judicial rescripts are among the best known that Umayyad caliphs sent, probably because of his prestige and authority among later Egyptians. Although other caliphs sent similar edicts to the provinces, ʿUmar II seems to have distinguished himself through his legal policy. His interest in prophetic traditions is well known, and he is remembered for the impetus he gave to the collection of ḥadīth, a task he apparently entrusted to the Medinan scholars Abū Bakr b. Muḥammad b. ʿAmr b. Ḥazm and al-Zuhrī. 64 Furthermore, he seems to have dispatched jurists to several provinces.

In Egypt, Yazīd b. Abī Ḥabīb is the most emblematic of these "imperial" jurists. Ibn Yūnus considers him as the first Egyptian scholar who set aside older apocalyptic narratives (malāḥim and fitan) in favour of traditions regarding the "lawful and the unlawful" (al-kalām fī l-ḥalāl wa-l-ḥarām wa-masāʾili-himā), and who promoted "ʿilm" (aẓhara l-ʿilm) in Egypt, perhaps in the sense of legal knowledge. More than a simple traditionist, as modern historians usually categorize him, he was also a jurist, and caliph ʿUmar II appointed him as "muftī" in Fusṭāṭ, alongside two other scholars. [START_REF]The last name is added by al-Dhahabī[END_REF] According to Ibn ʿAbd al-Ḥakam, he continued to report to the caliph, and even once asked the caliph his instructions regarding music played during weddings. [START_REF]al-Zubayr b. al-ʿAwwām 93/711-2 Medina (he stayed seven years in Egypt.) 2:147 Muḥammad b. Aws al-Anṣārī ? ? (became admiral of the Ifrīqī fleet in 93/711-2) 2:194 ʿUrwa b. Abī Qays, mawlā of ʿAmr b. al-ʿĀṣ c. 110/728-9 (classified as foreigner; however, son of Egyptian Abū Qays al-Sahmī)[END_REF] He held an official hearing (majlis) during which he answered legal questions brought by other scholars of Fusṭāṭ. 67 Furthermore, ʿUmar II apparently appointed ʿAbd Allāh b. Yazīd b. Khudhāmir as qadi of Fusṭāṭ, breaking with the usual selection of provincial qadis by local governors. According to al-Kindī, this Egyptian jurist had been part of a delegation sent to the previous caliph, Sulaymān b. ʿAbd al-Malik (r. 96-99/715-717), and was then spotted by ʿUmar b. ʿAbd al-ʿAzīz. 68 ʿUmar II thus distinguished himself by his personal handling of Egyptian legal affairs, in selecting a qadi and appointing a mufti who both shared his vision of Islamic law. Why did he appeal in Egypt to Yazīd b. Abī Ḥabīb? I would suggest that he intended to incorporate Fusṭāṭ into the imperial legal milieu that was increasingly important in the Eastern provinces, 64 Juynboll,Muslim Tradition,34;H. Berg,The Development of Exegesis in Early Islam: The Authenticity of Muslim Literature from the Formative Period (Richmond: Curzon, 2000), 7, 19, 28. 65 Ibn Yūnus,Taʾrīkh,1:509;6:32;1:299. See also Khoury, ʿAbd Allāh ibn Lahīʿa, 114-6. It is noteworthy that Yazīd b. Abī Ḥabīb is supposed to have transmitted ḥadīth from the Medinan scholar Nāfiʿ whom, according to Ibn Ḥajar, ʿUmar II sent to Egypt in order to teach sunan to the Egyptians. However, Juynboll doubts the authenticity of this report, as well as the historicity of this Successor, whose appearance as the "common link" in many isnāds could be a late rear projection. G.H.A. Juynboll, "Nāfiʿ," EI 2 , 7:878. [START_REF]al-Zubayr b. al-ʿAwwām 93/711-2 Medina (he stayed seven years in Egypt.) 2:147 Muḥammad b. Aws al-Anṣārī ? ? (became admiral of the Ifrīqī fleet in 93/711-2) 2:194 ʿUrwa b. Abī Qays, mawlā of ʿAmr b. al-ʿĀṣ c. 110/728-9 (classified as foreigner; however, son of Egyptian Abū Qays al-Sahmī)[END_REF] Ibn ʿAbd al-Ḥakam, Sīrat ʿUmar b. ʿAbd al-ʿAzīz, ed. Aḥmad ʿUbayd (n.l.: Maktabat Wahba, n.d.), 106. 67 Al-Kindī, Akhbār quḍāt Miṣr, 364. 68 Al-Kindī, Akhbār quḍāt Miṣr, 338; Ibn Yūnus, Taʾrīkh, 1:291. and from which Egypt was still isolated. ʿUmar b. ʿAbd al-ʿAzīz's interest in law is well known, and Arabic historiography presents him as surrounded by jurists when he was governor of Medina. [START_REF] See | ʿUmar II b. ʿAbd al-ʿAzīz[END_REF] In all likelihood, the caliph was attracted to the Medinan legal tradition, to the point that he later appears as a major authority in the Muwaṭṭaʾ of Mālik b. Anas. [START_REF] Borrut | Entre tradition et histoire: Genèse et diffusion de l'image de ʿUmar II[END_REF] Yazīd b. Abī Ḥabīb himself seems to have been one of the few Egyptian jurists trained in "foreign" legal thinking, especially that of Hijaz. Among his masters, Ibn Yūnus mentions the Medinan scholars Sālim b. ʿAbd Allāh (d. 107/725) , who probably visited Egypt, 72 and the Meccan jurist ʿAṭāʾ b. Abī Rabāḥ (d. 114-5/732-3). [START_REF] Yūnus | -Suyūṭī[END_REF] Yazīd b. Abī Ḥabīb's official appointment as mufti in Fusṭāṭ therefore appears to have been the deliberate introduction of a new legal tradition in Egypt, mostly inspired by Medinan law.

Other evidence suggests that ʿUmar II's policy reached North Africa, a newly conquered area, where he encouraged the development of a legal tradition in line with that of the imperial centre. Ḥabīb b. al-Shāhid al-Tujībī al-Miṣrī (d. 109/727-8), a scholar of Egyptian background, was part of a delegation sent to ʿUmar II, and became thereafter a famous faqīh, as authoritative in Tripoli as Yazīd b. Abī Ḥabīb was in Fusṭāṭ. 74 The same caliph is supposed to have sent "ten Successors" to Ifrīqiya to disseminate Islamic law, among them the Egyptian jurists Juʿthul b. Hāʿān al-Ruʿaynī (d. 115/733), Ḥibbān b. Abī Jabala al-Qurashī (d. 122/740), and Bakr b. Sawāda b. Thumāma al-Judhāmī (d. 128/745-6). 75 It is difficult to know whether North Africa was the subject of a specific policy, or whether data have been preserved for this part of the empire while they disappeared for others. In any case, it seems that Egypt played a significant role in shaping such policy, perhaps because of its geographical position, which made it the gateway to North Africa, or because of its cultural influence on Ifrīqiya. [START_REF] Djaït | L'Afrique arabe au VIIIe siècle (86-184 H./705-800)[END_REF] Did the caliph intend to harmonize-or even unify-Islamic law on an imperial scale? If so, his short reign did not give him enough time to achieve his reform. It is also worth asking why ʿUmar II in particular tried to implement such a policy. The case of Yazīd b. Abī Ḥabīb may offer a clue: according to later sources, this scholar retrospectively embodied a shift in Egyptian attitudes from apocalyptical expectations to legal concerns. Antoine Borrut has highlighted evidence that ʿUmar II ascended to the throne in a context of high messianic expectations, that is, on the eve of the hundredth anniversary of the hijra. The establishment of God's kingdom on earth by a rightly guided sovereign appeared as a necessary prerequisite for the apocalypse and the Last Judgment. However, in 99/717, the failure of the siege of Constantinople had called into question the caliphate's ability to impose its sovereignty over the whole world. [START_REF] Borrut | Entre mémoire et pouvoir: L'espace syrien sous les derniers Omeyyades et les premiers Abbassides[END_REF] This external failure could have caused a change in strategy. ʿUmar II now intended to assert himself as mahdī through his internal political agenda and, in particular, by the establishment of justice within the empire-which included not only his famous measures to redress the maẓālim (injustices) of his predecessors, but also his legal policy. 78 At the same time, the failure to take Constantinople led Muslims to postpone their apocalyptical expectations. No systematic legal system had been needed for administering a world that they believed was soon to disappear. Postponing the apocalypse to a later period required, however, a long-term social restructuring in accordance with divine will. If this analysis is correct, the reign of ʿUmar II thus represents a pivotal period, and his legal policy may reflect a more general change in the understanding of Islamic history, as Muslims rethought their eschatological expectations to give more space to daily rules governing this world.

At any rate, ʿUmar II's policy had a considerable impact on the Egyptian legal milieu. Al-Layth b. Saʿd, the most famous local jurist in the second half of the second/eighth century, was Yazīd b. Abī Ḥabīb's designated heir. In 128/745, when caliph Marwān II sent a new governor, al-Ḥawthara b. Suhayl al-Bāhilī, to restore order after a period of unrest, he commanded the elite of Fusṭāṭ to appoint a legal advisor who would "guide him (yusaddidahu) about legal cases (fī l-qaḍāʾ) and correct his opinions (yuṣawwiba-hu fī l-naẓar)," for the new governor was a rough "Bedouin." Both Yazīd b. Abī Ḥabīb and ʿAmr b. al-Ḥārith (d. 148/765), the other major Egyptian jurist of the time (who apparently visited Medina), [START_REF] About ʿamr | al-Ḥārith, mawlā of the Anṣār, see Ibn Yūnus, Taʾrīkh, 1:370-1; Ibn ʿAsākir[END_REF] agreed on their common student, al-Layth b. Saʿd, who thereby initiated his eminent career. 80 During the early Abbasid period, the doctrine of Medinan jurists, as transmitted by Ibn Abī Ḥabīb, was still a major reference in Fusṭāṭ. [START_REF]Akhbār quḍāt Miṣr[END_REF] Ibn Abī Ḥabīb had trained the qadi in office during the 760s, Abū Khuzayma Ibrāhīm b. Yazīd, who had the honour of opening his fatwā sessions. [START_REF][END_REF] His successor, the famous ʿAbd Allāh b. Lahīʿā (in office 154-165/771-2 to 780), had frequently visited Ibn Abī Ḥabīb in his youth, and the latter reportedly predicted his accession to the office of qadi. 83 As a child, qadi al-Mufaḍḍal b. Faḍāla (in office 168-169/785-786 then 174-177/790-793) had likewise been encouraged by the Egyptian master when he had asked him a question about a procedural rule. [START_REF]Akhbār quḍāt Miṣr[END_REF] Until the 780s, when the Abbasids tried to impose Ḥanafī or Mālikī jurists as judges in Fusṭāṭ, most qadis claimed to belong to Yazīd b. Abī Ḥabīb's tradition one way or another. Although the latter has been so far regarded primarily as a traditionist who introduced ḥadīth in Egypt, he was also-and perhaps more than anything else-a political tool used to bring Egyptian law in line with the Medinan tradition. The appointment of Yazīd b. Abī Ḥabīb as Egypt's official jurist reveals the promotion of a new generation of "imperial" jurists, and marks the formation of a "mixed" Egyptian school, halfway between local traditions and Medinan interpretations.

Medinan influence on the Egyptian scholarly milieu was reinforced in the second half of the eighth century, partly in connection with Abbasid legal policy. Eager to base their legitimacy on the promotion of a legal system, the first Abbasid caliphs first turned to Medinan jurists, among whom they recruited several qadis before turning more resolutely to the Iraqi scholarly milieu. 85 The growing prestige of Mālik b. Anas, who attracted disciples from all over the dār al-islām, also played a major role in spreading his knowledge on an imperial scale. By the dawn of the ninth century, Egyptian law had mainly become proto-Mālikī, before al-Shāfiʿī's followers took over.

Conclusion

During the second half of the first/seventh century, a juristic milieu emerged in Fusṭāṭ, based on the teaching of the Companions and, among them, the governor ʿUqba b. ʿĀmir. This legal tradition is little known. Because of incompatibilities between this "school" and the basic principles of classical fiqh, its influence on the development of Islamic law was either minimal or erased from the collective memory. It was later relegated to the dustbin of history on the pretext that it only dealt with eschatological expectations. Although this view may exaggerate historical reality, the belief in the imminence of the world's ending and the Last Judgment may have led the first generations of Egyptian scholars to emphasize this issue rather than rules governing the social organization of a community that was destined to disappear soon.

In the first half of the second/eighth century, under the Marwānids, Egyptian jurists still appeared relatively isolated from the intense legal discussions that were now taking place in other parts of the Middle East. When presenting the opinions of the main Umayyad legal circles, early Abbasid sources only give a very marginal place to Egyptian jurists, whose interactions with "foreigners" were apparently limited. Such relative isolation is, at the current state of research, difficult to explain. Could one argue that scholars' circulation in search of religious knowledge (ṭalab al-ʿilm) was at that time more limited than is often thought? Should we rather consider the characteristics of Fusṭāṭ's population? Mainly inhabited by Yemeni tribes originating from the south of the Arabian Peninsula, the Egyptian capital had not sheltered a large number of major Companions after its foundation, which perhaps did not make it an attractive destination for eastern scholars. For their part, Yemeni scholars in Egypt, who had developed a distinctive culture marked by high eschatological expectations, might have been less sensitive to religious knowledge as it was developing further east. We may finally hypothesize that population flows related to the ongoing conquests also played a role in this phenomenon. While men of Arabia, Syria and Iraq were involved together in expeditions against territories to the north (Byzantium) and the east of the dār al-islām, Egyptians were more likely to participate in the conquest of western territories. This may explain the existence of strong interactions between scholars of originating from the former territories, and the relative isolation of Egyptians. All these hypotheses remain so far speculative. 85 Tillier,Les cadis d'Iraq et l'État abbasside,[148][149][150][151][152][153][154][155][156][157] However, judicial practices reveal that legal interactions actually existed between Egypt and the rest of the empire. Procedures implemented in Fusṭāṭ and elsewhere were quite similar, Medina being closest in comparison. Egyptian law was primarily integrated into the rest of the Umayyad Empire through institutions. Caliph ʿUmar II b. ʿAbd al-ʿAzīz played a leading role in this process by offering an official position to Yazīd b. Abī Ḥabīb, a local jurist from Fusṭāṭ also trained in Medinan law. By introducing elements of Medinan legal culture into Egyptian law, Ibn Abī Ḥabīb laid the foundations of a "reformed" Egyptian school, influenced by the legal tradition of Medina, in which the major Egyptian jurists of the next generation trained. This school seems therefore to have resulted from a policy of legal harmonization within the Umayyad Empire. It survived into the second half of the eighth century-when its main representative, al-Layth b. Saʿd, was still discussing the relationships between local Egyptian tradition and Medinan law-before giving way to the Mālikī and Shāfiʿī schools, both inherited from Medinan legal culture. 32 Al-Suyūṭī, Ḥusn al-muḥāḍara, 1:207. 33 The last three names are given by al-Dhahabī, Taʾrīkh al-islām, 3:378. 34 Al-Dhahabī relates that he was head of the arsenal where warships were built. Al-Dhahabī, Taʾrīkh al-islām, 3:442. 35 Ibn Yūnus, Taʾrīkh, 1:297; al-Suyūṭī, Ḥusn al-muḥāḍara, 1:260. [START_REF] Al-Ṣanʿānī | 1; Ibn Ḥazm[END_REF] See also his biography in al-Kindī, Wulāt, 85-6; al-Maqrīzī, al-Muqaffā l-kabīr, 3:273-6. 37 These two names are provided by al-Dhahabī, Taʾrīkh al-islām, 3:711. 38 ʿAbd Allāh b. Wahb (Egyptian) 48 39 Al-Maqrīzī, al-Muqaffā l-kabīr, 3:784. [START_REF]9:404. 42 Ibn ʿAsākir[END_REF] This list is provided by al-Dhahabī, Taʾrīkh al-islām, 3:937. 41 This list is provided by al-Dhahabī, Taʾrīkh al-islām, 3:937. 42 The last two names are given by al-Dhahabī, Taʾrīkh al-islām, 3:870. [START_REF] Al-Quḍāt | [END_REF] Al-Dhahabī, Taʾrīkh al-islām, 3:870. 44 Ibn Yūnus, Taʾrīkh, 1:333; al-Suyūṭī, Ḥusn al-muḥāḍara, 1:299. 45 Ibn Yūnus, Taʾrīkh, 2:72; al-Suyūṭī, Ḥusn al-muḥāḍara, 2:299. See Khoury, ʿAbd Allāh ibn Lahīʿa, 113. [START_REF] Shayba | ʿAbd Allāh Nadhīr Aḥmad[END_REF] Ibn Yūnus, Taʾrīkh, 1:244; al-Suyūṭī, Ḥusn al-muḥāḍara, 1:280. [START_REF] Al-Ṣanʿānī | [END_REF] The last three names are given by al-Dhahabī, Taʾrīkh al-islām, 4:166.

Name

  ʿAbd Al-Raḥmān b. Jubayr (d. 97 or 98/715-6 or 716-7), another early "jurist" identified by Ibn Yūnus, reportedly transmitted the knowledge of the same ʿUqba b. ʿĀmir. 14 7 See Annex 1. 8 Ibn Yūnus, Taʾrīkh, 1:315. A close supporter of ʿAlī at the beginning of the fitna, Ibn Muljam (d. 40/661) turned against him along with other Kharijis after the battle of Ṣiffīn, and murdered him in 40/661. On ʿAbd al-Raḥmān b. Muljam, see also al-Maqrīzī, al-Muqaffā l-kabīr, ed. Muḥammad al-Yaʿlāwī (8 vols., Beirut: Dār al-gharb al-

  , 531; Ibn ʿAbd al-Ḥakam, Futūḥ Miṣr wa-akhbāru-hā, ed. Ch.C. Torrey (New Haven: Yale University Press, 1922), 294; Ibn ʿAsākir, Taʾrīkh madīnat Dimashq, ed. ʿUmar b. Gharāma al-ʿAmrawī (80 vols., Beirut: Dār al-fikr, 1995), 40:486; Ibn al-Athīr, Usd al-ghāba fī maʿrifat al-ṣaḥāba, ed. ʿAlī Muḥammad Muʿawwaḍ and ʿĀdil Aḥmad ʿAbd al-Mawjūd (8 vols., Beirut: Dār al-kutub al-ʿilmiyya, n.d.), 4:51; Ibn Ḥajar, al-Iṣāba fī tamyīz al-ṣaḥāba, ed. ʿĀdil Aḥmad ʿAbd al-Mawjūd and ʿAlī Muḥammad Muʿawwaḍ (8 vols., Beirut: Dār al-kutub al-ʿilmiyya, 1995), 4:429. See R.G.

  Marthad b. ʿAbd Allāh al-Yazanī (d. 90/709) 12 Ḥabīb b. al-Shahīd al-Tujībī al-Miṣrī (d. 109/727-8) 16 [Ḥibbān?] b. Abī Jabala al-Qurashī (d. 122/740) 1 Yazīd b. Abī Ḥabīb (d. 128/745-6) 71 Bakr b. Sawāda b. Thumāma al-Judhāmī al-Miṣrī (d. 128/745-6) 5 ʿAbd Allāh b. Abī Jaʿfar Yasār (d. 129/746-7) 1 Saʿīd b. Abī Ayyūb al-Khuzāʿī (d. 162 or 166/778-9 or 782-3) 25 Ibrāhīm b. Nashīṭ b. Yūsuf al-Waʿlānī (d. c. 163/779-80) 1 ʿUthmān b. al-Ḥakam al-Judhāmī al-Miṣrī (d. 163/779-80) 2 Sulaymān b. Abī Dāʾūd al-Ḥamrāwī al-Miṣrī (d. 168/784

  Number of individual masters who transmitted to Egyptian jurists (death dates of the masters) Egyptians Hijazis

  Al-Kindī recounts for example a marital dispute brought before the qadi ʿAbd Allāh b. Yazīd b. Khudhāmir (in office 100-105/719-724), in which the latter ignored both the legal rule and the procedure that he should follow: Ibn Qudayd reported from Aḥmad b. ʿAmr b. al-Sarḥ, from Ibn Wahb, from ʿAbd al-Aʿlā b. Saʿīd al-Jayshānī, from Muḥammad b. ʿIkrima al-Nahrī:

  of Egyptian Fuqahāʾ who Died before 200 H., Mentioned as such by Ibn Yūnus 1 Nota bene: Unless another reference is given, death dates and regional identifications rely on the information provided by al-Dhahabī in Taʾrīkh alislām. . Mālik al-Jayshānī (Egyptian) 3 ʿAbd al-Malik b. Malīl al-Salīḥī (Egyptian) 4 ʿAbd al-Raḥmān b. ʿĀmir al-Hamdānī (Egyptian?) Kathīr b. Qulayb al-Ṣadafī (Egyptian) 5 Abū Qabīl al-Maʿāfirī (Yemen, then Egypt) 6 Jubayr b. Nufayr (Ḥimṣ)

  al-ʿĀṣ (d. 43/663) (Egyptian) ʿAbd Allāh b. ʿAmr (d. 65/684-5?) (Egyptian) ʿUqba b. ʿĀmir (d. 58/677-8) (Egyptian)

  Taʾrīkh, 1:403; al-Kindī, Wulāt, 22-2.

  of his masters and disciples it too long to be included in this table. Al-Dhahabī cites the following masters: ʿAṭāʾ b. Abī Rabāḥ (d. 114-5/732-3) (Meccan), Nāfiʿ (d. 117/735?) (Medinan), Ibn Abī Mulayka (d. 117/735) (Meccan), Saʿīd al-Muqriʾ, Abū l-Zubayr [Muḥammad b. Muslim] (d. 128/745-6) (Meccan), al-Zuhrī (d. 124/742) (Medinan), Mishraḥ b. Hāʿān (d. c. 120/738) (Egyptian), Abū Qabīl al-Maʿāfirī [Ḥayy b. Hāniʾ] (d. 128/745-6) (Yemen, then Egypt), Yazīd b. Abī Ḥabīb (d. 128/745-6) (Egyptian), Bukayr b. ʿAbd Allāh b. al-Ashajj (d. 127/744-5?) (Medina, then Egypt), Jaʿfar b. Rabīʿa [al-Kindī] (d. 134/751-2?) (Egyptian), ʿAbd al-Raḥmān b. al-Qāsim (d. 126/743-4) (Medinan), Darrāj Abū l-Samḥ (d. 126/743-4) (Egyptian), al-Ḥārith b. Yaʿqūb [al-Anṣārī] (d. 130/747-8) (Egyptian), ʿUbayd Allāh b. Abī Jaʿfar (d. 136/753-4?) (Egyptian), ʿUqayl b. Khālid (d. 144/761-2?) (Ayla?-Egypt), Ayyūb b. Mūsā (d. 133/750-1) (Meccan), Bakr b. Sawāda (d. 128/745-6) (Egyptian), al-Julāḥ Abū Kathīr (d. 120/738) (Egyptian), al-Ḥārith b. Yazīd al-Ḥaḍramī (d. 130/747-8) (Egyptian), Khālid b. Yazīd (d. 139/756-7) (Egyptian), Khayr b. Nuʿaym (d. 137/754-5) (Egyptian), Ṣafwān b. Salīm (d. 124/741-2) (Medinan), Abū l-Zanād [ʿAbd Allāh b. Ḏakwān] (d. 131/748-9?) (Medinan), ʿAbd al-Raḥmān, Qatāda (d. 117/735?) (Baṣran), Muḥammad b. Yaḥyā b. Ḥibbān (d. 121/739) (Medinan), Yaḥyā b. Saʿīd [al-Anṣārī] (d. 143/760-1?) (Medinan), Yazīd b. [ʿAbd Allāh b.] al-Hād (d. 139/756-7) (Medinan), Muḥammad b. ʿAjlān (d. 148/765-6) (Medinan). His main disciples are: Muḥammad b. ʿAjlān (Medinan), Ibn Lahīʿa (Egyptian), Ibn al-Mubārak (from Marw; he visited Egypt), Ibn Wahb (Egyptian), Shabāba [b. Sawwār] (al-Madāʾin), Ḥujayn b. al-Muthannā (Yemen, then Baghdad), Saʿīd b. Abī Maryam (Egyptian), Ādam b. Abī Iyās (Marw-Baghdad-ʿAsqalān), Aḥmad b. Yūnus, Shuʿayb b. al-Layth (Egyptian), Yaḥyā b. Bukayr (Egyptian), Yaḥyā b. Yaḥyā al-Laythī (Cordoba), Yaḥyā b. Yaḥyā al-Tamīmī al-Khurāsānī (Khurāsān-Hijaz-Iraq-Syria-Egypt), Abū l-Jahm al-ʿAlāʾ al-Bāhilī (Baghdadī), Qutayba b. Saʿīd (Balkh), Muḥammad b. Rumḥ (Egyptian), Yazīd b. Mawhab al-Ramlī (Ramla), Kāmil b. Ṭalḥa (Baṣra-Baghdad), ʿĪsā b. Ḥammād (Egyptian). Al-Dhahabī, Siyar aʿlām al-nubalāʾ, 4:710. 68 Ibn Yūnus, Taʾrīkh, 1:328. 69 Al-Dhahabī, Siyar aʿlām al-nubalāʾ, 6:89. 70 Al-Dhahabī cites the following masters: Yūnus b. Yazīd (d. 159/775-6) (Ayla), Ibn Jurayj (d. 150/767) (Meccan), Ḥayy b. ʿAbd Allāh al-Maʿāfirī (d. ?) (Egyptian ?), Ḥanẓala b. Abī Sufyān (d. 151/768) (Meccan), ʿAmr b. al-Ḥārith (d. 148/765-6) (Egyptian), Usāma b. Zayd al-Laythī (d. 153/770) (Medinan), ʿUmar b. Muḥammad al-ʿUmarī (d. 150/767-8) (Medina-ʿAsqalān), ʿAbd al-Ḥamīd b. Jaʿfar (d. 153/770) (Medinan), Abū Ṣakhr Ḥamīd b. Ziyād (d. ?) (Egyptian), ʿAbd Allāh b. ʿĀmir al-Aslamī (d. 150/767-8?) (Medinan), Mūsā b. ʿAlī [al-Lakhmī] (d. 163/779-80) (Egyptian), al-Layth [b. Saʿd] (d. 175/791-2) (Egyptian), Mālik [b. Anas] (d. 179/795) (Medinan). His main disciples are : al-Layth b. Saʿd (d. 175/791-2) (Egyptian), Aṣbagh b. al-Faraj (Egyptian), Abū Ṣāliḥ, Aḥmad b. Ṣāliḥ (Egyptian), Ḥarmala [b. Yaḥyā] (Egyptian), al-Ḥārith b. Miskīn (Egyptian), Yaḥyā b. Ayyūb al-Maqābirī (Baghdādī), Baḥr b. Naṣr al-Khawlānī (Egyptian), al-Rabīʿ b. Sulaymān al-Murādī (Egyptian), Yūnus b. ʿAbd al-Fuqahāʾ Dead before 200 H. who Visited Egypt or Settled There, Mentioned by Ibn Yūnus Name Date of death Origin

  Their marginal presence in the two Muṣannafs becomes evident when comparing these figures with citations of a few leading Iraqi, Syrian, and Medinan jurists of the same period:

	Other jurists	Citations in both Muṣannafs
	Ibn Abī Laylā (Kūfa)	670
	Ibn Sīrīn (Baṣra)	1530
	Makḥūl (Damascus)	480
	Saʿīd b. al-Musayyib (Medina)	823
	-

1

  This list is based on all the entries in which someone is said to be faqīh (or min [al-]fuqahāʾ), muftī, or to have been trained in fiqh (tafaqqaha). Other scholars who may also have been trained in fiqh but are not described as such by Ibn Yūnus are not listed here. Names of jurists recorded in this list are in bold.

	Name Name	Date of death Date of death	Reference in Ibn Yūnus Reference in Ibn Yūnus	Learned from Learned from	Taught to Taught to
				Abū Saʿīd al-Khudrī (d. 64/684?) (Medinan) 17	Abū ʿUshshāna Ḥayy b. Yuʾmin (Egyptian)
				Abū Ayyūb al-Anṣārī (d. 52/672?) (came to	Abū Qabīl Ḥayy b. Hānī' al-Maʿāfirī (Egyptian)
				Egypt) 19	Baʿja al-Juhanī (Hijaz)
				Abū Baṣra al-Ghifārī (d. ?) (settled in Egypt) 20	[Abū] Saʿīd al-Maqburī (Medinan)
	Marthad b. ʿAbd Allāh al-Yazanī	90/708-9	1:467		ʿUlayy b. Rabāḥ (Egyptian) Abū l-Khayr Marthad al-Yazanī (Egyptian) 7
				ʿUthmān b. ʿAffān (d. 35/656) (Medinan)	ʿAbd al-Raḥmān b. Hurmuz al-Aʿraj (Medinan origin; came
				ʿAlī b. Abī Ṭālib (d. 40/661) (Medina-Kūfa)	to Alexandria) 10
	Nāʿim b. Ujayl al-Hamdānī al-Miṣrī (mawlā)	80/699-700	1:491	Ibn ʿAbbās (d. 68/687-8) (Hijaz) Kaʿb b. ʿAdī (d. ?) (Ḥīra; came to Egypt) 8	Yazīd b. Abī Ḥabīb (Egyptian) Al-Ḥārith b. Yazīd (Egyptian) 11
				Abū Hurayra (d. 58/678?) (Medinan)	ʿUbayd Allāh b. al-Mughīra (Egyptian) 12
				ʿAbd Allāh b. ʿAmr (d. 65/684-5?) (Egyptian) 9	Kaʿb b. ʿAlqama (Egyptian)
				ʿUthmān (d. 35/656) (Medinan)	Yaʿlā b. ʿAṭāʾ (d. 120/738) (Wāsiṭī, originally from Ṭāʾif) 14
	Abū ʿAlqama al-Fārisī al-Miṣrī (mawlā)	? (became a qadi of Ifrīqiya)	1:523	Ibn Masʿūd (d. 32/652-3) (Kūfī) Abū Hurayra (d. 58/678?) (Medinan) Abū Saʿīd al-Khudrī (d. 64/684?) (Medinan) 13	Sharāḥīl b. Yazīd al-Maʿāfirī (d. af. 120/738) (Egyptian) 15 Ṣāliḥ b. Abī Maryam (d. c. 100/718-9) (Baṣrī) Abū l-Zubayr al-Makkī (d. 128/745-6) (Meccan)
					ʿAbd al-Raḥmān b. Ziyād (d. 156/772-3) (Ifrīqī) 16
	Abū l-Najīb Ẓalīm al-ʿĀmirī	88/707	1:248	Ibn ʿUmar (d. 73/693) (Medinan)	Bakr b. Sawāda (Egyptian) 18
	7 The last seven names are cited by al-Dhahabī, Taʾrīkh al-islām, 2:523.
	8 Al-Suyūṭī, Ḥusn al-muḥāḍara, 1:229.
	9 The last name is given by al-Dhahabī, Taʾrīkh al-islām, 2:885.
	10 Ibn Yūnus, Taʾrīkh, 2:126; al-Suyūṭī, Ḥusn al-muḥāḍara, 1:345.
	11 Ibn Yūnus, Taʾrīkh, 1:101; al-Suyūṭī, Ḥusn al-muḥāḍara, 1:257. See Khoury, ʿAbd Allāh ibn Lahīʿa, 110.
	12 Ibn Yūnus, Taʾrīkh, 1:334; al-Suyūṭī, Ḥusn al-muḥāḍara, 1:276.
	2 Al-Suyūṭī, Ḥusn al-muḥāḍara, 1:259. 13 These four names occur in al-Dhahabī, Taʾrīkh al-islām, 3:193.
	3 Al-Suyūṭī, Ḥusn al-muḥāḍara, 1:295. 14 Al-Dhahabī, Taʾrīkh al-islām, 3:342.
	4 Ibn Ḥibbān, al-Thiqāt, ed. Sharaf al-Dīn Aḥmad (9 vols., Beirut, Dār al-fikr, 1975), 5:122. 15 Ibn Yūnus, Taʾrīkh, 1:229; al-Suyūṭī, Ḥusn al-muḥāḍara, 1:274.
	5 Ibn Yūnus, Taʾrīkh, 1:406.
	6 Al-Suyūṭī, Ḥusn al-muḥāḍara, 1:298.
				20

16

The last three names occur in al-

Dhahabī, 3:193. 18

Al-Dhahabī, Taʾrīkh al-islām, 2:1034.

 Akhbār quḍāt Miṣr, 313.

On ʿUqba b. ʿĀmir, see M. Tillier, "Une tradition coranique égyptienne? Le codex de ʿUqba b. ʿĀmir al-Ǧuhanī," Studia Islamica, 117 (2022), 38-63.

 17 SeeKhoury, ʿAbd Allāh ibn Lahīʿa, 91,

99.18 See

Annex 2.19 Yaḥyā b. Maʿīn, Taʾrīkh Ibn Maʿīn (riwāyat al-Dūrī), ed. Aḥmad Muḥammad Nūr Sayf (4 vols., Mecca: Markaz al-baḥth al-ʿilmī wa-iḥyāʾ al-turāthal-islāmī, 1979), 4:487-90; al-Fasawī, Kitāb al-maʿrifa wa-l-taʾrīkh, ed. Akram Ḍiyāʾ al-ʿUmarī (3 vols., s.l.: Muʾassasat al-risāla, 1981)

, 1:689-90.20 I have shown in a previous study that in the early Abbasid period, the qadis of Fusṭāṭ followed procedures similar to those prescribed by Medinan jurists(Tillier, "Les '

premiers' cadis," 216).

Juynboll, Muslim Tradition,83.

M. Tillier, "Scribes et enquêteurs: Note sur le personnel judiciaire en Égypte aux quatre premiers siècles de l'hégire," Journal of the Economic and Social History of theOrient 54 (2011), 391-7.

 Akhbār quḍāt Miṣr, 344.

 Akhbār quḍāt Miṣr, 351.

Appendix 2 Transmission of Knowledge among Egyptian Fuqahāʾ

Bibliography

Primary Sources


Hugo Laplagne

Gwenola Touzot-Jourde

Delphine Holopherne-Doran

Cédric Du- Mas
email: cedric.dumas@imt-atlantique.fr

Epidural motor skills measurements for haptic training

Keywords: epidural, force feedback, needle insertion, haptic training

Epidural procedure can be a challenging skill to learn. Veterinarians must feel how many ligaments they get through before performing the injection in the exact location, relying solely on haptic perception, on a wide range of animal sizes. Force, torque, and position sensors were mounted on a needle to measure an epidural injection procedure. We provide here the data analysis that led to the needle insertion force profile extraction, to be used in procedural haptic simulators.

Introduction

There are many types of medical tools used in different procedures. Physicians conducting such procedures sense the interaction between the medical tool and the deformable specimen through haptic perception. One of the medical fields that requires high haptic sensitivity of the physicians is anaesthesiology. Epidural Analgesia is commonly performed in animals and taught in all veterinarian schools. This procedure is rarely image-guided and requires high haptic sensitivity to get through the tissue layers to perform the injection in the exact body space (the vertebral canal).

The Epidural technique data collection

Epidural needle insertion was performed on an anaesthetized dog in a veterinarian school on two occasions. The needle was modified to contain position and forces sensors in order to get two sets of corresponding data. Each experiment was documented with video, and complemented with CAT-Scans of the dog from the side as well as from top showing the steps of the procedure during the second experiment. The time scale of the data extends on around two minutes and a half. However, during the second experiments breaks were taken to take the pictures via CAT-scans and therefore the force data cannot be used to reproduce the interventional skill with a high fidelity as the needle was left dangling. The purpose of this data collection was to build training material for the students. Haptic and spatial measurements were meant to model the epidural skill. This paper focus on the first dataset that can be used to characterize motor skills to perform adequately the epidural needle insertion. The data analysis provided here in terms of haptic measurements is meant to help building epidural skills training tools (virtual simulator, haptic device, or any other mean). This measurement consists of one directional force and position profile to characterize the sensitivity of layers perforations.

Anatomy

The epidural injection is a locoregional anesthetic technique that is commonly performed for pain management during veterinary surgical procedures on the hindlimbs as well as for humans mostly during labor. In small animal species like dogs and cats, animals are already under general anesthesia to ease the performance of this intrusive procedure on a still body. This operation consists in delivering a combination of local anesthetic and analgesic drugs in the epidural space in the low back at level of the intervertebral space between L7 and S1, which are respectively the last lumbar vertebra and the first sacral vertebra [START_REF] Halley | Epidural Analgesia in the Dog[END_REF]. The very end of the spinal cord covered by the meninges sits at this level, making this procedure delicate and challenging. The needle has to cross 4 different tissues to get into the epidural space: the skin which provides for the first resistance; the supraspinous ligament and the interspinous ligament which offer the second resistance and then the ligamentum flavum that seems to provide the third and harder resistance. Three different Cat-Scans were taken during the second experiment (see figure 1) at each three key steps of the procedure: after the skin, before the ligamentum flavum; and after the ligamentum flavum in the epidural space. We can observe that the trajectory seems curved, due to the fact that the needle was left hanging before taking the pictures and the weight of the sensors made it tilt. Epidural injection techniques are a widely studied interventional skill (over 16,000 references in PubMed). In his survey on epidural simulators [START_REF] Vaughan | A review of epidural simulators: Where are we today?[END_REF], Neil Vaughan concludes "the ideal epidural simulator […] would contain a force feedback haptic device, with force data originating from measured Tuohy needle insertions from patient". Our study is meant to extract an accurate enough epidural insertion force profile to be trusted by experts when using in a simulator. Despite recent advances in virtual and real (3D printed) simulators [START_REF] Neves | 3D anatomical model for teaching canine lumbosacral epidural anesthesia[END_REF][START_REF] Jeong | A proposal of a simple epidural simulator for training novice anesthesiologists[END_REF], often for human size and anatomy, they do not focus on haptic accuracy: once the skin is passed with the needle, feeling the successive ligaments perforation is a real challenge for novices (or experts with infrequent practice). Notwithstanding ligament perforation can require little force [START_REF] Lynch | Measurement of forces from epidural catheter insertion[END_REF], added frictions increase the epidural complexity: frictions between the needle and the animal tissue increase while being inserted forward. Our study focuses on procedural skills and training haptic sensitivity, as veterinarians only rely on haptic feeling to perform injection in the proper space, with the added constraints of being able to adapt to various animals size and anatomy.

Proposed Method

The measurements were setup in an operating room of the Nantes veterinarian school (see figure 2) with a C-arm, a motion tracking device, and a haptic sensor, described in the section below.

Figure 2: the operating room

OptiTrack

The position data sensor is an OptiTrack system, which gets the position data with infrared reflectors mounted on the needle, and a set of three FlexV100 cameras around the operating table (Figure 3). The infrared reflectors were placed on top of the needle.

The four dots on the sensor constitute a tetrahedron of which centre is the point that is used to determine coordinates in the frame of reference. The tetrahedron indicates the rotational coordinates around each axis consecutively x, y and z. The frame of reference was placed on the table with axes x and z being horizontal and y being the vertical axis. Between the needle and the handle with the infrared reflectors, a force sensor is mounted to measure the forces applied to the needle. A Labjack U6 analog to digital acquisition board was used to record the ATI Nano17 transducer, the smallest commercially available 6-axis force sensor (see Table 1). The removable needle guide, situated into the lumen of the needle shaft, was modified and fixed inside the needle. The guide is usually here to help the needle pass through tissue without clogging and is removed to inject the drugs. For this sensor, the axis from the base to the tip of the needle is called the z axis.

Retrieving and pre-treatment

The data is returned from the experiment in an xml file, using the open source HaCoE software [START_REF] Hacoe | Haptic perception measurement software for research[END_REF] and the architecture seen in Figure 4. After doing so, a quick plot of the data along the time shows that the position and orientation data. Position data are noised with a lot of its value being 9999.0 (no measurement) due to the occlusion of the needle from the cameras, that can happen during the procedure when the anaesthesiologist is moving the needle around. The force sensor has no such error with continuous measurements. A simple filter of the position data removing records with coordinate x above 100 was sufficient to remove the OptiTrack errors.

Synchronisation between videos, images and records was performed to identify which time window corresponds to the needle insertion. The recorded data file provides a hundred and fifty seconds long sequence, where the video of the procedure only lasts for thirty-eight seconds. To identify which part of the data coincides with the needle insertion, we looked at the force along the needle's axis and its fluctuations. By looking at this graph (figure 5) we can safely assume that the operation happens in the seventyeight to one hundred seconds time frame. Once this time frame is identified, we just proceed to filter the torques and forces with a simple low-pass filter using the left rectangle numerical method:

𝑠 𝑖 = 𝑠 𝑖-1 + 𝑇𝑒 𝜏 × (𝑠𝑡 𝑖-1 -𝑠 𝑖-1 ) 𝜏 = 1 2 × 1 𝜋 × 𝑓 𝑐
Where s is the filtered signal, st is the original signal, f_c is the filtering frequency and Te is the sampling period. By trial and error, and looking at the graph, we use this filter to suppress high frequency noise without losing too much of the original information. We chose 0.75 Hz filtering frequency. Better filters and better frequency determination methods could be used to lose even less of the data and to provide a better filtering method.

Geometrical transformation

We observed on the videos of the operation the needle is rotated often, so the tip of the needle and the handle have very different trajectories. We assumed that the needle is rigid, and we extrapolate the tip of the needle position from the measured handle position (where the IR reflectors are mounted).

In order to do so, we used the data provided by the OptiTrack. Using homogenous coordinates [START_REF] Hughes | Computer Graphics: Principles and Practice[END_REF] and the OptiTrack documentation [START_REF]OptiTrack Documentation Wiki[END_REF], we create a transformation matrix. Knowing the tetrahedron and the needle geometries, the OptiTrack sensor rotation and translation, we computed the needle tip position. From this we created a 3D plot of to check if the needles movement corresponds to the expectations (Figure 8). From the 3D plot and the variation along each axis, we can say that the variations are contained within the margins of length expected by the veterinarian which are between 5 to 6 centimetres (Figure 8), considering that there are also parasitic lateral movements around the insertion axis and that the there is some margin around the actual needle insertion movement. To detect any error in this procedure, we created a function that computes, for each point of the needle tip calculated, the distance between this point and the handle. We checked this distance had no variation in length.

Principal component analysis

In order to extrapolate a one-dimensional direction profile for the needle and focus on insertion force along this axis, we used a method called principal component analysis to isolate a direction along which to project each point. The Principal Component Analysis (PCA) is a reduction method applied on a dataset to identify the principal components along which the data is differentiated and therefore distinguishable. It computes the eigenvalues and eigenvectors of the dataset's covariance matrix to identify the principal components [START_REF] Gray | Principal Component Analysis: Methods, Applications and Technology[END_REF]. This method is widely used in data science for linear regression, which is the goal we pursue here.

We implemented the PCA with the estimated point of insertion coordinates (cf. section 4.2). To calculate this point, we found the first variation of the force and defined it as the needle point of insertion (figure 9 bottom).

Discussion

PCA Limitations

As we can observe on (see figure 10), the results of the PCA are far from the expected results as we have variations on a length of almost twelve centimeters for the onedimensional movement. Also, it would be expected for the needle to progress along the axis only to be pulled out when the procedure is done, hitting a plateau whenever the veterinarian stops to force the needle through a tissue that presents a resistance. Instead, this plot shows a needle that would be inserted then pulled back to be inserted further again. The problems to solve here are to use force, torque and position data together to create a more accurate insertion force profile, that compensates lateral movements of the needle.

3.2. Force modifications

As we can observe on (see figure 9) that the force does not render the idea of three resistance plateaus but more of isolated peaks of exerted force from the veterinarian. This seems counter intuitive to a simple rectilinear movement, however, as previously said, the movement isn't rectilinear. Indeed, watching the video one can observe the operator moves the head of the needle around while trying to feel where and how to insert the needle at every step of the way. If we look at the torque while the force is at a local minimum, we can see that a strong torque is measured most of the time (figure 10). This can be explained by the fact that the operator turns the needle while not moving. And this torque when impacting the force may cause this irregular profile. As a way of correcting those irregularity and creating a more accurate insertion force profile, we cancel the torque which would normally translate as: (-𝑇𝑥 + 𝑇𝑦) × 𝑙 where l is the needle's length. When analysing the movements, we can set an approximative time gap of five seconds between the skin and the second resistance encountered and a fifteen seconds gap between the skin and the third resistance. Therefore, we have peaks of force that are coherent with the three timestamps of insertion and resistance met during the operation (as seen on figure 11). The incertitude on the data is the peak of force that indicates a traction of the needle by the skin. Although the epidural space has a negative pressure, the needle does not seem to be in the epidural space. This irregularity might be caused by a poor filtering of the torque, as we can see very high torque at this point.

Conclusion

Despite being able to measure force and torque on the needle with a highly sensitive sensor, performed by an expert anaesthesiologist able to compensate the tool weight variation, it was not straightforward to extract the force profile along the needle insertion axis. Nevertheless, the calculated force profile (figure 11) can be used to measure or train students haptic sensitivity, for example with simple 1D haptic devices. We can further improve the correction to create the three proper peaks although we know data accuracy is counter balanced by expert perception: from previous studies [START_REF] Dumas | Haptic feedback tuning in colonoscopy simulation[END_REF], we know that, once inserted in a simulator, force profiles need to be tuned by experts before they trust the simulation and actually use it with trainees. The following step is then to check this first force profile with the experts.

Future Work

Based on this preliminary work, we have conducting new research on two tracks. The first one is measuring the same epidural procedure at the vet school with a cow, to get a force profile with a significant different physiology.

The second one is to build a new haptic device to train vet students to improve their performance with ligaments perforation. A first prototype has been built (see photo on the left) with an ATI Nano 17 6D force sensor and a FAULHABER linear DC servomotor LM1247-020-12. The displacement and the force feeling are smooth. It has to be evaluated now with vet students.

Figure 1 :

 1 Figure 1: top view before and after needle insertion

Figure 3 :

 3 Figure 3: (left) the original epidural needle with mounted force sensor and infrared reflectors (right) motion tracking cameras frame of reference

Figure 4 :

 4 Figure 4: block diagram of the apparatus

Figure 5 :

 5 Figure 5: graphs of the force insertion profile (Fx, Fy, Fz)

Figure 6 :

 6 Figure 6: Graphs of torque along the x axis (blue) and the filtered torque (orange) at 0.5 Hz, 0.01 Hz and 0.001 Hz filtering frequencies

Figure 7 :Figure 8 :

 78 Figure 7: coordinates (X,Y,Z) of needle extremity in the global frame if reference

Figure 9 :

 9 Figure 9: (top) Graph of the projected position along the principal component over time (bottom) Graph of the force insertion profile Fz along the needle axis over time Most data treatment coding languages -mainly Python and Matlab -have built-in methods to implement the PCA. Here we used numpy.linalg.svd from NumPy, the fundamental package for scientific computing in Python. Once we implemented the PCA, we can directly plot the projected data and its variations during the timeframe (figure 9 top).

Figure 10 :

 10 Figure 10: Graph of the force (Fz) along the needle axis and torques normal to the needle (Tx, Ty) over time

  Figure 11: (top) Graph of the projected position along the principal component over time (bottom) Graph of the force with torque compensated over time.

Table 1 .

 1 Force (F) and Torque (T) characteristics of the ATI Nano17

		CALIBRATION		SENSING RANGES		RESOLUTION
		REFERENCE	Fx, Fy	Fz	Tx, Ty	Tz	Fx, Fy, Fz	Tx, Ty, Tz
		SI-12-0.12	12 N	17 N	120 Nmm	120 Nmm	1/320 N	1/64 Nmm
	4	Results