Abū ‘Abd Allāh Muḥammad ibn Sa‘d ibn Manī‘ al-Baṣrī al-Hāshimī kātib al-Wāqidī or simply Ibn Sa'd (Arabic: ابن سعد) and nicknamed "Scribe of Waqidi" (Katib al-Waqidi), was a scholar and Arabian biographer. Ibn Sa'd was born in 784 CE (168 AH) and died in 845 CE (230 AH). Ibn Sa'd was from Basra, but lived mostly in Baghdad, hence the nisba al-Basri and al-Baghdadi respectively. He is said to have died at the age of 62 in Baghdad and was buried in the cemetery of the Syrian gate. Ibn Sa'd was also a proponent of the Muʿtazila doctrine of the created Quran and supported the king Al-Ma'mun's stance on the matter.
The Book of the Major Classes (Arabic: Kitab Tabaqat Al-Kubra) is a compendium of biographical information about famous Islamic personalities. This eight-volume work contains the lives of Muhammad, his Companions and 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. 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".