Kitāb al-Ṭabaqāt al-Kabīr of Ibn Saʿd, a Source for Nahj al-Balāgha

The compiler of Nahj al-Balāgha, Sharif al-Radi (d. 406 AH), rarely mentioned his sources and most of the contents of this literary work are without mentioning the sources. Nevertheless, the efforts of several contemporary researchers have led to the identification of some sources of Nahj al-Balāgha. The seventy-seventh letter has one of the famous phrases and it is the advice of Imam Ali (a.s.) to Ibn Abbas when he was sent to talk with the Khawarij, which is often cited. In the source studies of Nahj al-Balagha, so far, only some sources have has been recognized, which all were written after al-Radi. The present study, while introducing other sources, first deals with the question of what was the source of Suyuti (d. 911 AH) and why did it was challenged by some researchers? This research shows that the Kitāb al-Ṭabaqāt al-Kabīr of Ibn Sa‘d (d. 230 AH) was most likely a direct or indirect source for Radi. Also, while examining the existing editions of the book and its defects, it is clear that the manuscripts of a part of the book have been unknown until now. So, it was not available to previous researchers and has been neglected. Due to the fact that there are doubts about the attribution of this text to Amir al-Mu’minin, this article has paved the way for further investigation of this issue by introducing the source of Letter 77.