He was a leading jurist (faqih), legal theoretician (usuli), Arabic grammarian, (nahwi), Qu'ran exegete (mufassir) and a scholar of theology, man of letters, and Hadith.
[1] He was born in the villages of Juwayn in modern-day northeastern Iran, grew up in there, and read literature under his father Yusuf bin Abdullah, Abi Yaqoub.
[1] He settled in Nishapur after his intense educational journeys and began to issue fatwas, teach, and debate in the year 407 of Hijri.
"[7] Al-Sabuni said: "If Shaykh Abu Muhammad had been born among the Israelites, they would have transmitted his immense merits to us and he would have made their pride.
"[1] Ibn Asakir narrates from his maternal uncle, `Abd al-Wahid ibn `Abd al-Karim al-Qushayri the son of Imam Abu al-Qasim: "In his time our [Ash`ari and Shafi`i] imams and the verifying scholars among our companions saw in him such perfection and high merit that they used to say: If it were permissible to hold that Allah sent another prophet in our time, it would not have been other than he.