Abū ʿĀṣim al-Ṣaydilānī, al-Ḥusayn ibn Muḥammad ibn Matt, and a host of the scholars of Herat.
He was one of the authorities to whom people referred for diagnosing hidden defects in hadith and for narrator criticism and validation.
He died in the year 429 AH.
A copy of his book Al-Ramī has reached us.

377 – ʿAbd al-Qāhir ibn Ṭāhir, Abū Manṣūr al-Baghdādī*
A consummate scholar, brilliant polymath, and eminent professor, Abū Manṣūr al-Baghdādī settled in Khurasan. He produced a number of remarkable works and was counted among the leading figures of the Shāfiʿī school.
He transmitted hadith from Ismāʿīl ibn Nujayd, Abū ʿAmr Muḥammad ibn Jaʿfar ibn Maṭar, Bishr ibn Aḥmad, and their peers.
Hadith were transmitted from him by Abū Bakr al-Bayhaqī, Abū al-Qāsim al-Qushayrī, ʿAbd al-Ghaffār ibn Muḥammad al-Shīrawayh, and many others.
He was the most senior of the students of Abū Isḥāq al-Isfarāyinī. He used to teach seventeen different disciplines, to the point that his breadth of knowledge became proverbial. A dignified and affluent leader, he wrote a work entitled Al-Takmilah on arithmetic.
Abū ʿUthmān al-Ṣābūnī said: “The master Abū Manṣūr was among the foremost authorities in uṣūl (the foundations of the religion).”