Ibn Sa'd

Abu Abd Allah Muhammad ibn Sa'd (born 168 AH / 784 CE in Basra, died 230 AH / 845 CE in Baghdad) was an Iraqi scholar of the early Abbasid period, remembered above all as a compiler of biographies. He carried the nisbas al-Basri (from his birthplace) and al-Hashimi, the latter because his family were mawali — clients — of the Banu Hashim. He is most often called Katib al-Waqidi, "the secretary of al-Waqidi," after the celebrated Medinan historian whose assistant and transmitter he became in Baghdad; the title signals both his closeness to al-Waqidi's material and the place he made his home.

His enduring work is the Kitab al-Tabaqat al-Kabir (often al-Kubra), "The Great Book of Generations" — tabaqat meaning "classes" or "generations" of scholars. Arranged in successive cohorts, it gathers a biography of the Prophet Muhammad together with thousands of notices on the Companions, the Followers, and later transmitters, and it remains a foundational source for early Islamic history.

Later hadith critics generally regarded him as reliable, though some were uneasy with him because of the mihna, the Abbasid "inquisition" under the caliph al-Ma'mun over whether the Qur'an was created or uncreated. He is reported to have been among scholars questioned in that affair; sources differ on exactly what he professed, and the episode should be read as a reported controversy rather than a settled judgement on his views. He was buried, it is said, in Baghdad's cemetery at the Syrian Gate (Bab al-Sham).