Da'a'im al-Islam (Arabic: دعائم الإسلام lit.
[1] The book was written by Al-Qadi al-Nu'man.
[1] The book emphasizes what importance Islam has given to manners and etiquette along with Ibadah, the worship of God, citing references of first five Fatimid imams and earlier Shia imams, Imam hasan,Imam hussain,Imam ali zainul abedin,Muhammad al-Baqir and Jafar-as-Sadiq.
[1] Subsequent Fatimid imams and caliphs and Ismaili dai's have relied on Da'a'im-ul-Islam'.
The 16th Fatimid imam — Caliph Al-Hakim bi-Amr Allah (996–1021) — ordered his da'i, Harun bin Mohammed in Yemen, to give decisions in light of Da'a'im al-Islam only.