Ibn Sa'd

Muhammad ibn Sa'd ibn Mani' al-Zuhri al-Basri al-Baghdadi was the secretary (katib) of al-Waqidi. His masterwork al-Tabaqat al-Kubra (The Great Classes) is the most comprehensive biographical dictionary of the Prophet ﷺ, his Companions, the Tabi'in, and subsequent generations. It runs to 8 volumes (in modern editions, much more in manuscript) and is an essential source for Islamic biographical literature (tarjama). He died in Baghdad in 230 AH.