Abu Ali Sina, Pur Sinа, and often known in the West as Avicenna

Religion

A number of theories have been proposed regarding Avicenna's madhab (school of thought within Islamic jurisprudence). Medieval historian Ẓahīr al-dīn al-Bayhaqī (d. 1169) considered Avicenna to be a follower of the Brethren of Purity. On the other hand, Dimitri Gutas along with Aisha Khan and Jules J. Janssens demonstrated that Avicenna was a Sunni Hanafi. Avicenna studied Hanafi law, many of his notable teachers were Hanafi jurists, and he served under the Hanafi court of Ali ibn Mamun. Avicenna said at an early age that he remained "unconvinced" by Ismaili missionary attempts to convert him. However, the 14th century Shia faqih Nurullah Shushtari according to Seyyed Hossein Nasr, claimed he was a Twelver Shia.^[37] Conversely, Sharaf Khorasani, citing a rejection of an invitation of the Sunni Governor Sultan Mahmoud Ghazanavi by Avicenna to his court, believes that Avicenna was an Ismaili.^[38] Similar disagreements exist on the background of Avicenna's family, whereas most writers considered them Sunni, recent Shiite writers contested that they were Shia.^[25]