al Mufid

Abu 'Abd Allah Muhammad ibn Muhammad ibn al-Nu'man al-'Ukbari al-Baghdadi known as al-Shaykh al-Mufid and Ibn al-Mu'allim for his expertise in philosophical theology (c. 948-1022 CE) was an eminent Twelver Shi'ite theologian.
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Abu Abdullah Muhammad al-Harithi al-Baghdadi al-Mufid (lived 10th century), Iraqi scholar and jurist.
The Book of Guidance into the Lives of the Twelve Imams "The Life of the Commander of the Faithful"

Al-Shaikh al-Mufid's full name was Muhammad b. Muhammad b. Nu'man al-Harithi al-Baghadi al-'Ukbari; his kunya was Abu 'Abd Allah. As well as being called al-Shaikh al-Mufid, he was known in both Shi'i and non-Shi'i circles as Ibn al-Mu'allim. He was born in the year 338 A.H./949 and was brought up in a village. His father brought him to Baghdad for his education. There he studied under Shi'i and Mu'tazili scholars. He showed such promise that one of his teachers recommended that he study under one of the leading scholars of the period, 'Ali b. 'Isa al-Ramani. He also studied under the leading Shi'i traditionists of the time, al-Shaikh al-Saduq.
It is said that al-Mufid earned his title of al-Mufid as a result of a dispute about the relative merits of the two events - Ghadir Khumm and the Cave.
Al-Mufid soon became one of the foremost scholars of his time. He was an outstanding theologian and jurist, and a brilliant polemical writer on behalf of the Shi'ites. He became head of the Shi'i scholars in Baghdad and took part in many debates and discussions with his opponents.
The writings of al-Shaikh al-Mufid were numerous. Al-Tusi tells us in the Fihrist that they numbered nearly two hundred. A number of these still survive; some have been published and some are still in manuscript form. Among them is al-Muqni'a, a work on tradition, which al-Tusi used as the basis for his great work Tahdhib al-ahkam fi sharh a/-munqi'a.[5] In theology, we are left with an important treatise Awa'il al-maqalat, where al-Mufid discusses Shi'i theology in relation to other schools; this work has been recently studied by a leading French scholar.
Al-Shaikh al-Mufid died in the month of Ramadan in the year 413 A.H./1022. One report says that over 80,000 people attended his funeral.