ibn Muḥammad ibn al-Qāsim ibn Muḥammad ibn Sayyār, the client of the Umayyad caliph al-Walīd ibn ʿAbd al-Malik. He was Andalusian, Cordoban, known as al-Bayyānī, and counted among the leading authorities.

His mastery of fiqh and its debated questions so overshadowed his knowledge of ḥadīth that he outstripped the scholars of his time. His scholarly leadership became proverbial, and he rose to the rank of a mujtahid imam who practiced no blind imitation, despite his strong inclination toward the Shāfiʿī school and his penetrating grasp of it. He had devoted himself to studying under the two imams Abū Ibrāhīm al-Muzanī and Muḥammad ibn ʿAbd Allāh ibn ʿAbd al-Ḥakam.

Birth: after the year 220 AH, as far as I can determine.

He transmitted ḥadīth from Ibrāhīm ibn Muḥammad al-Shāfiʿī, Abū Ṭāhir ibn al-Sarḥ, Ibrāhīm ibn al-Mundhir al-Ḥizāmī, al-Ḥārith ibn Miskīn, Yūnus ibn ʿAbd al-Aʿlā, al-Muzanī, al-Rabīʿ, Ibn ʿAbd al-Ḥakam, and many others.

He also met the last remaining disciples of al-Layth and Mālik.

The scholars of Córdoba acquired their jurisprudence from him.

Among those who narrated from him were Saʿīd ibn ʿUthmān al-Aʿnāqī, Aḥmad ibn Khālid ibn al-Jabbāb, Muḥammad ibn ʿUmar ibn Lubābah, his son Muḥammad ibn Qāsim, Muḥammad ibn ʿAbd al-Malik ibn Ayman, and others.

Ibn al-Farḍī says in his History: “Qāsim al-Bayyānī attached himself to Ibn ʿAbd al-Ḥakam for the sake of jurisprudence and debate; through him and through al-Muzanī he became firmly grounded. He followed the method of evidence and rational inquiry, abandoned taqlīd, and inclined toward the fiqh of al-Shāfiʿī… he was not” — and the statement continues.