He authored numerous works, among them Darajāt al-Tāʾibīn (The Ranks of the Penitent), which is transmitted by Abū al-Waqt from ʿAbd al-Aʿlā on his authority.

He occupied a leading place in several fields and was unrivalled in asceticism and devotion.

He also composed a book on the Merits of al-Shāfiʿī (1).

The ḥadith master Yūsuf b. Aḥmad al-Shīrāzī said: “He was an imam in a number of sciences—among them the Qurʾānic readings, hadith, jurisprudence, the meanings of the Qurʾān, and literature—and he produced superb works in each. He likewise wrote al-Jamʿ bayna al-Ṣaḥīḥayn (The Reconciliation of the Two Ṣaḥīḥs) with full isnāds. In renunciation and detachment from worldly things he was a sign unto himself, yet the marketplace of Herāt found no demand for his virtues, for at that time all the acclaim belonged to Yaḥyā b. ʿAmmār (2).”

Abū ʿAmr b. al-Ṣalāḥ said: “I examined Abū Muḥammad al-Qarrāb’s work entitled al-Kāfī fī ʿIlm al-Qurʾān (The Adequate Guide to Qurʾānic Studies) in several volumes; it is a delightful book, brimful of knowledge. In his Merits of al-Shāfiʿī he says, ‘I met a group of the students of Ibn Surayj (3).’”

Al-Qarrāb had studied jurisprudence in Baghdad under Imām ʿAbd al-ʿAzīz al-Dārakī (4).