Abu Nu'aym al-Isfahani

Abu Nu'aym Ahmad ibn Abdullah al-Isfahani (336–430 AH / 948–1038 CE) was a Sunni traditionist (muhaddith, a transmitter and critic of hadith — reports of the Prophet Muhammad's words and deeds) and biographer based in Isfahan, in Persia, then under Buyid rule. He came from a family already steeped in learning; his grandfather is reported to have led a circle of devout ascetics in the city. Following the standard scholarly practice of his age, he traveled in search of hadith (rihla), journeying as a young man through Khuzestan, Iraq, and the Hijaz, and later through the Caspian region and Khurasan, collecting reports from a vast network of teachers. He is traditionally said to have held transmission licenses from hundreds of authorities, and later masters such as al-Khatib al-Baghdadi rated him highly as a hadith scholar.

His most influential work is Hilyat al-Awliya' wa-Tabaqat al-Asfiya' ("The Ornament of the Friends of God"), a ten-volume collection of biographies and sayings of early pious figures, ascetics, and Sufis. It remains a major—if much-debated—source for the early history of Sufism.

In legal matters he is generally classed as a Shafi'i, and several sources place him within the Ash'ari theological school. On that basis he clashed with the Hanbali traditionist Ibn Manda and his followers in Isfahan, who are reported to have barred him from the city's congregational mosque. The two camps' mutual accusations are positions held by rival schools, not settled facts.