Tabaqat Ibn Sa'd (Al-Tabaqat al-Kubra)

الطبقات الكبرى

The earliest biographical dictionary of the Prophet, his Companions, and the Tabi'in arranged in generational layers (tabaqat). Ibn Sa'd, a student of al-Waqidi, compiled detailed biographies of thousands of early Muslims, preserving information about their lineage, conversion, participation in battles, narration of hadith, and personal qualities. An indispensable source for the study of early Islamic history.