[5] Ibn Sa'd was from Basra,[2] but lived mostly in Baghdad, hence the nisba al-Basri and al-Baghdadi respectively.
The Major Book of Classes) is a compendium of biographical information (tabaqāt) about famous Islamic personalities.
This eight-volume work contains the lives of Muhammad, his Companions and his Helpers, including those who fought at the Battle of Badr as a special class, and of the following generation, the Followers, who received their traditions from the Companions.
[7] Ibn Sa'd's authorship of this work is attested in a postscript to the book added by a later writer.
In this notice he is described as a "client of al-Husayn ibn ‘Abdullah of the ‘Abbasid family".