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Abu Hanifa al-Nu‘man ibn Muhammad ibn Mansur ibn Ahmad ibn Hayyun al-Tamimi, generally known as al-Qāḍī al-Nu‘mān also Qadi Noman (died 974 CE/ 363 AH) was an Isma'ili jurist and the official historian of the Fatimid caliphs.Syedna Qadi Noman was also called Qadi Quddat and Dai Duat.
Born in Qayrawan, North Africa, he converted to Isma'ili Islam and began his career in Ifriqiya (modern-day Tunisia, western Libya and eastern Algeria) under the first caliph, al-Mahdi Billah (r. 909-934 CE/ 297-322 AH), quickly rising to become the most prominent judge (qadi) of the Fatimid state. During his lifetime, he served four Fatimid Caliphs:
In his fifty years of service to the Fatimids, he wrote a vast number of books under the encouragement of the caliphs on history, biography, jurisprudence (fiqh) and the interpretation of scripture (ta'wil). After the Fatimid conquest of Egypt and Syria, al-Nu'man left Ifriqiya and travelled to the newly founded city of al-Qahira (Cairo) where he died in 974 CE/ 363 AH. 
Under Al-Mahdi began the career of Qadi Al-Numan (d. 974), the founder of Ismaili law and author of its most authoritative compendium, the Kitab da'a'im Al-Islam (Book of the buttresses of Islam). In the absence of an Ismaili legal tradition, Qadi Al-Numan relied primarily on the legal teaching of Imams Muhammad Al-Baqir and Jafar Al-Sadiq, transmitted by Twelver Shii traditionists, and secondarily on Zaydi traditions. As a former Maliki jurist, he was evidently also influenced by Maliki legal concepts.
In substance Ismaili law naturally agrees closely with Twelver Shii law, it prohibits, however, the temporary marriage (mut'ah) allowed in the latter and nullifies bequests to a legal heir except when consent of the other legal heirs is obtained. It gives the imam authority for determining the beginning of the month without regard to the sighting of the new moon as required by all other Muslim legal schools. Since the early Fatimid period the beginning of the months was generally established in practice on the basis of astronomical calculation and thus often fell one or two days earlier than for other Muslims; this discrepancy often caused intercommunal quarrels about the beginning and end of the fasting month of Ramadan.
Al-Nu'man's most prominent work, the Daim al-Islam (Arabic:دعائم الاسلام)('The Pillars of Islam'), which took nearly thirty years to complete, is an exposition of the Fatimid jurisprudence. The work that was finally completed during the reign of the fourth caliph, al-Mu'izz li-din Allah (r. 953-975 CE/ 341-365 AH), was accepted in its time as the official code of the Fatimid state, and serves to this day as the primary source of law (sharia) for some Mustaali Isma'ili communities, especially the Tayyibis. Iran has incorporated Daim-ul-Islam into their constitution.
Another major work, the Kitab iftitah al-da‘wa wa-ibtida’ al-dawla (The Beginning of the Mission and Establishment of the State) narrates the rise of the Fatimids, including the initial stages of the Isma'ili da'wa in Yemen under Ibn Hawshab; Abu 'Abdullah al-Shi'i's correspondence with the Kutama Berber tribes and their military expeditions leading to the conquest of the Aghlabid empire; al-Mahdi Billah's emigration from Salamiya, his captivity in Sijilmasa and eventual release, culminating in the establishment of the Fatimid state in 909 CE. The book also gives an account of the circumstances leading to the revolt of al-Shi'i, for which it holds responsible the incitement of his elder brother Abu al-Abbas, and his later execution. It also gives a description of the Fatimid state up to the year 957, when the book was completed.
Ikhtilaf usul al-madhahib (Differences Among the Schools of Law) was a refutation of Sunni principles of jurisprudence, written at roughly the same time as the earliest of such works. Nu'man's book borrows heavily from those of Dawud al-Zahiri, Muhammad bin Dawud al-Zahiri and Muhammad ibn Jarir al-Tabari, three Sunni authors about whom Nu'man displays complex mixed feelings. It has been noted that while Nu'man's book is famous, it was not the first Ismali refutation of Sunni juristic principles.
Al-Nu'man's other major works are the Kitab al-majalis wa’l-musayarat (The Book of Sessions and Excursions, in which he has entailed in detail words of Imams in Majalis, or just while walking which he had taken note of, and the wisdom encased within them) and the Kitab al-himma fi adab atba‘ al-a’imma (The Book of Etiquette Necessary for Followers of the Imams).
- Between revolution and state: the path to Fatimid statehood: Qadi Al-Nu'man and the construction of Fatimid legitimacy by Sumaiya A. Hamdani. London; New York: I.B. Tauris; London: In association with The Institute of Ismaili Studies, 2006.
- Daftary, Farhad (2006). The Biographical Encyclopaedia of Islamic Philosophy (PDF) (Oliver Leaman ed.). Continuum International Publishing Group. Retrieved 19 June 2015.
- Life of Syedna Qadi Nauman (R.A.)
- Fyzee, Asaf A. A. The Book of Faith: Translated from the `Da'im al-Islam' of Qadi Nu'man. Bombay: Nachiketa Publication Ltd., 1974.; Brief History of the Life of Syedna Qadi Nauman ,by Shaikh Saifuddin Rashid
- Devin J. Stewart, "Muhammad b. Dawud al-Zahiri's Manual of Jurisprudence." Taken from Studies in Islamic Law and Society Volume 15: Studies in Islamic Legal Theory. Edited by Bernard G. Weiss. Pg. 116. Leiden: 2002. Brill Publishers.