He was addressed by the kunya Abū ʿAbdillāh. He was a freedman of the Shaybān tribe. He was a student of Abū Ḥanīfa. His origins were from the villages of al-Shām (Greater Syria). His father had come to Iraq. He himself was born in the city of Wāsiṭ in the year 132 of the Hijra, and was raised in Kūfa; he studied under Abū Ḥanīfa, Misʿar, Thawrī, ʿUmar b. Dharr, and Mālik b. Mighwal. He transmitted from Mālik b. Anas, Awzāʿī, and Abū Yūsuf. He settled in Baghdad, where he narrated hadith. When Imām Shāfiʿī came to Baghdad in the year 184 of the Hijra, he wrote down what he heard from him. Hārūn al-Rashīd appointed him as qāḍī (judge) of Raqqa, but later removed him from this position.
Muhammad b. Hasan b. Zufar used to say to his family: "Do not ask me for any worldly needs. If you do, you occupy my qalb (the heart). But take as much as you wish from my wealth and money. For these concern me very little. If my wealth and money are lost, it hardly affects me at all, and my qalb is not attached to wealth or money."
Imām Shāfiʿī said about him: "I have not seen a scholar as profound as him."
"I have not seen anyone as light-spirited, nor as eloquent as him. When I listened to his recitation of the Qur'an, I felt as if the Qur'an had been revealed in his tongue. I have not seen anyone more intelligent than him. He satisfied both the eye and the soul."
Ṭaḥāwī said: "Imām Shāfiʿī requested the book of Siyar from Muhammad b. Hasan, but Muhammad b. Hasan did not fulfill this request. Thereupon, Imām Shāfiʿī wrote him the following note:
'Say to the man whom my eyes have not seen the like of; so that whoever sees him, sees those before him. Knowledge prevents scholars from withholding knowledge from students. Knowledge must be transmitted to students, so that they may transmit it to those who are worthy.'
Upon this note, Muhammad b. Hasan b. Zufar immediately sent the requested book to Imām Shāfiʿī as a gift."
Ibrāhīm al-Ḥarbī said: "They asked Imām Aḥmad b. Ḥanbal:
- From where did you learn these subtle matters?
- I learned them from the books of the late Muhammad b. Hasan." As mentioned in previous paragraphs, Muhammad b. Hasan b. Zufar and Kisāʾī died on the same day in this year.
Upon his death, Hārūn al-Rashīd said: "Today, the sciences of language and fiqh (Islamic jurisprudence) have been buried together."
He was fifty-eight years old when he died.