Al-Nu'man's work consists of over 40 treatises on fiqh, history, religious beliefs and Quranic esoteric exegesis.
Fuat Sezgin cites 22 works by him. Al-Nu'man's most prominent work, the ''
Da'a'im al-Islam'' ( "The Pillars of Islam"), which took nearly thirty years to complete, is an exposition of Isma'ili jurisprudence. This work 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 Caliphate, and serves to this day as the primary source of religious law (
sharia) for some
Musta'li communities, particularly
Tayyibi Isma'ilis.
Iran incorporated the ''Da'a'im al-Islam'' into their constitution. The book consists of 32 chapters in two volumes. The first volume consists of 7 chapters discussing the
Seven pillars of Ismailism. The second volume consists of 25 chapters about various topics relating to different facets of life. Alongside his
Pillars of Islam, the
Foundation of Symbolic Interpretation (
Asās al-Taʾwīl), is one of al-Nu’man's most celebrated works and deals with esoteric interpretation (
taʾwīl). In the author's own words, “Our aim [with the
Asās al-Taʾwīl] is to explain the
inner dimension (
bāṭin) of what we laid out in the book
Daʿāʾim al-Islām, so that this book may be a source for the inner meaning (
bāṭin), just as that one is for the
external form (
ẓāhir). Qadi al-Nu'man believed that it is important to recognize and understand the symbolism behind the stories in the
Quran based on certain verses that point to an inner meaning such as: “Thus your Lord will choose you and teach you the symbolic interpretation (
taʾwīl) of events (
aḥadīth)” (Quran 12:21). In his work
Foundation of Symbolic Interpretation (
Asās al-Taʾwīl), he indicates that
God made the
Quran the miracle of
Muhammad and its inner meaning the miracle of the
Imams. Just as nobody can replicate the miracle of the
Book, nobody can produce its inner meanings except for the
Imams. This sacred knowledge is passed down through generations in their lineage and is entrusted to them. 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. It mentions the initial stages of the Isma'ili
dawah in
Yemen under
Ibn Hawshab. It also discusses
Abu Abdallah al-Shi'i's correspondence with the
Kutama Imazighen and their military expeditions, leading to the conquest of the
Aghlabids, who ruled Ifriqiya. It discusses Imam al-Mahdi's emigration from
Salamiyah, his captivity in
Sijilmasa and eventual release, culminating in the establishment of the Fatimid state in 909. 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 Islamic 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
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
majlis, 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"). ==Further reading==