Ahmad ibn Ibrahim al-Naysaburi

Aḥmad ibn Ibrāhı̄m al-Nı̄sābūrı̄ or al-Naysābūrı̄ (Arabic: أحمد بن إبراهيم النيسابوري; fl. late 10th century/early 11th century) was an Isma'ili scholar from Nishapur, who entered the service of the Fatimid caliphs al-Aziz Billah and al-Hakim bi-Amr Allah in Cairo. His life is relatively obscure, and is known chiefly from references in his works. Among them three stand out as highly important for Fatimid and Isma'ili history: the Istitār al-imām, a historical work that offers unique information on the early history of the Isma'ili movement and the rise of the Fatimid Caliphate, the Risāla al-mūjaza, which contains an exposition on the qualities and duties of the ideal Isma'ili missionary, and the Ithbāt al-imāma, an influential analysis of Isma'ili conceptions of the imamate, combining rationalist philosophical argument with Islamic theology.