Al-Mu'ayyad fi'l-Din al-Shirazi
Al-Mu'ayyad fid-din Abu Nasr Hibat Allah b. Abi 'Imran Musa b. Da'ud ash-Shirazi (c. 1000 CE/390 AH – 1078 CE/470 AH) was an 11th-century Isma'ili scholar, philosopher-poet, preacher and theologian of Persian origin. He served the Fatimid Caliph-Imām al-Mustansir Billah as a "Da'i" in varying capacities, eventually attaining the highest rank of "Bab al-Abwab" "The Gate of Gates" and "Da'i al-du'at" "Chief Missionary" in the Fatimid "Da‘wah". In his theological and philosophical writings he brought the Isma'ili spiritual heritage to its pinnacle. Life. Al-Mu'ayyad was  born in Shiraz not later than 387/997 and died in Cairo in 470 AH/1078 AD. He lived during the time of the Fatimid Caliphs Al-Hakim (386–412 AH / 996–1021 AD), Al-Zahir (412–427 AH / 1021–1036 AD) and Al-Mustansir (427–48AH / 1036–1094AD). He was buried in the Dar al-ilm where he had resided, worked and died. Al-Muayyad's real name was Hibatullah ibn Musa, born in the town of Shiraz, capital of the Fars Province (then Persia, now in modern-day Iran), in the year 1000 CE. His father, Musa ibn Dawud, served under the Fatimid Caliph-Imam al -Hakim bi Amr Allah as the Chief Missionary of the province of Fars, where the Isma'ili mission was active. Al-Muayyad was "contemporary with the changeover from the Buyid to the Saljuq Sultanate under the Abbasid Caliphate, as well as the Arab bedouin Hilalian invasion of North Africa, the Fatimiid encouraged invasion of Baghdad by al-Basasiri, the Battle of Manzikert in Anatolia, the rise of the Sulayhids of Yaman and the advent of the Armnenian General Badr al-Jamali in Egypt". During the reign of the Fatimid Caliph-Imam al-Zahir li-i'zaz Din Allah, Hibatullah ibn Musa was  permitted to take over the "da'wah" office from his father. His title, "Al-Mu'ayyad fi d-Din" ('The one aided in religion') was probably accorded to him around this time. Al-Mu'ayyad was appointed to the Diwan al-insha' (secretariat) in 440 AH / 1048 AD on a monthly salary of 1000 dinars and wrote the religious sermons (al-Majalis) for al-Yazuri (as-Sira 89–90). Al-Mu'ayyad gives us an interesting information about the presence of a Buyid Prince Abu 'Ali in the Fatimid Court (as-Siras 87). Al-Muayyad (Hibatullah) gradually worked his way up the hierarchy of the  da‘wa and was eventually appointed Chief Missionary under the Caliph-Imam al-Mustansir Billah. He was appointed the head of the Academy of Science (Dar al-'Iim, originally been founded by the Caliph al-Hakim in Cairo), which was also the headquarters of the Da'wa and became the residence of al-Mu'ayyad. He directed the Da'wa affairs throughout the Fatimid sphere of influence particularly Persia, Yaman, Bahrayn and Northern and Western India ('Uyun - ms. - fols. 59-63, 65). In this position, he worked teaching missionaries from both inside and outside the Fatimid Empire and composing his theological works until the end  of his life in 1078 CE. He founded the dynamic tradition of "Fatimid daʿwa" ('religious mission') poetry that flourished after him for a thousand years through the succeeding Taiyabi daʿwa and continues to thrive today. His poetry uses a unique form of esoteric tāwīl-based religious symbolism – metaphor, in fact, as manifestation, where what appears to be metaphor is the theological reality of the Imam. The primary source for details of Al-Mu'ayyad's life are his own memoirs, the "Sirat al-Mu'ayyad fi d-Din", which was written in three stages between the years 1051 and 1063 CE. He  is also mentioned in the works of Nasir Khusraw, another prominent Isma'ili scholar of the time, who had learned under al-Mu'ayyad. In a poem written in 455/1063 (Diwan, 173–177) Nasir praises al-Mua-yyad as his master (teacher) and refers to him as the "Warden of the Gate" ('Bab'). There are other direct references in Nasir's Diwan (313–314). Al-Mu'ayyad also taught Hassan-i Sabbah.