He mastered the craft of making locks so thoroughly that he fashioned a complete lock—with all its parts and its key—that weighed only four grains. When he turned thirty, sensing in himself an extraordinary intelligence, he developed a love for jurisprudence (fiqh). He therefore devoted himself to its study until he excelled, becoming a byword for mastery, and he is the originator of the Khurasani method in jurisprudence (1).

He studied under Abu Zayd al-Fashani (2), receiving instruction and hadith from him as well as from al-Khalil ibn Ahmad al-Sijzi, and he attended hadith sessions in Bukhara and Herat.

Among those who studied with him were Abu ʿAbd Allah Muhammad ibn ʿAbd al-Malik al-Masʿudi, Abu ʿAli al-Husayn ibn Shuʿayb al-Sinji, and Abu al-Qasim ʿAbd al-Rahman ibn Muhammad ibn Furan al-Marawazi.

The jurist Nasir al-ʿUmari said, “In the time of Abu Bakr al-Qaffal no one was more versed in jurisprudence than he, and no one like him will appear after him. We used to say that he was an angel in human form. He transmitted hadith, dictated lessons, stood at the pinnacle of fiqh, and was a model of asceticism (3).”

Abu Bakr al-Samʿani said in his Amali: “He was unrivalled in his age in jurisprudence, memorization, piety, and renunciation. Within the school (madhhab) he left behind works unmatched by any of his contemporaries, and his refined method (4) in the Shafiʿi school—passed down by his students—is the soundest and most thoroughly substantiated. Jurists traveled to him from distant lands, and eminent imams graduated under his tutelage.”