He remained there during the subsequent reign of al-Hakim bi-Amr Allah (r. 996–1021), rising to what, according to the historian Paul E. Walker, appears to have been a high-ranking position in the Isma'ili daʿwa.
[6] His work Istitār al-imām wa tafarruq al-duʿāt fi’l-jazāʾir li-ṭalabih ("[Book on the] Concealment of the Imam and the Dispersal of Dāʿīs in Search of Him to Different ‘Islands’"), usually shortened to Istitār al-imām, is a significant historical source on the early history of the Isma'ili movement, the early schism that resulted in the flight of Abdullah al-Mahdi Billah, from the Isma'ili headquarters at Salamiyya, and his journey to North Africa, where he established the Fatimid Caliphate in 909.
[2][7][8] It also contains the first public version of the Fatimid dynasty's official genealogy, possibly published, as the historian Michael Brett suggests, as a reaction to the anti-Fatimid Baghdad Manifesto issued by the Abbasid caliph al-Qahir in 1011.
[15] Written sometime between 1013 and 1015,[16][17] it emphasizes the strict obedience owed by the dāʿī to the Caliph-Imam, and considers all other authorities illegitimate; as Michael Brett writes, his strategy aimed to "win recruits against the time when the lords of the land would be either converted or overthrown".
[20] A facsimile edition was published in Verena Klemm, Die Mission des fatimidischen Agenten al-Mu’ayyad fi'ddin in Siraz (Frankfurt, Peter Lang, 1989), pp.
[22] It was written in an atmosphere of deep crisis in the Isma'ili daʿwa, created by Caliph al-Hakim's erratic changes in both doctrine and governance, and is an attempt to reaffirm, in the words of Brett, "the necessity of belief in the Imam as the source of knowledge and the authority for the law".
[24] It was published by M. Ghalib, Beirut, 1984,[25] and in a critical edition with an English translation by Arzina R. Lalani, in Degrees of Excellence: A Fatimid Treatise on Leadership in Islam.