Hibatullah ibn Musa Abu Nasr al-Mu'ayyad fi d-Din ash-Shirazi (1000–1078 CE) was an 11th century Isma'ili scholar, philosopher-poet, preacher and theologian of Persian origin. He served the Fatimid Caliph-Imam Ma'ad 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 ad–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.
Hibatullah ibn Musa was 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.
During the reign of the Fatimid Caliph-Imam Ali az-Zahir, 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.
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. In this position, he worked at the Dar al-'Ilm "House of Knowledge" teaching missionaries from both inside and outside the Fatimid Empire and composing his theological works until the end of his life in 1078 CE.
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.
- Majalis ul-Muayyadiyah
- Diwan ul-Muayyad, a collection of poems in praise of the Ismai'ili Imams and the doctrines of their faith
- Sirat al-Muayyad fid-Din, his autobiography
- Sarah ul-Maad, a treatise on the Day of Resurrection
- Al-Eazah watabeer fi Fazle Yoomal Ghadir, a treatise on the Ghadir Khumm incident
- Al-Ibteda wal-Inteha (lit. the Beginning and the End)
- Taweel ul-Arwah, a treatise on souls
- Mahajul-Ibadah, the method of devotion
- Al-Maselet-wal-Jawab (lit. Questions and Answers)
See also 
Nasir Khusraw Ismailism
- ^ VERENA KLEMM,"MOʾAYYAD FI’L-DIN ŠIRĀZI" in Encyclopaedia Iranica
- Verena Klemm (2003). Memoirs of a Mission: The Ismaili Scholar, Statesman and Poet, al-Mu’ayyad fi’l-Din al-Shirazi. Ismaili Heritage Series 9, London: I. B. Tauris in association with The Institute of Ismaili Studies. ISBN 978-1-86064-432-0.
- Tahera Qutbuddin (2005). Al-mu'ayyad Al-shirazi And Fatimid Da'wa Poetry: A Case Of Commitment In Classical Arabic Literature. Brill Academic Publishers. ISBN 978-90-04-14103-2.
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