Muhammad ibn Umar al-Kashshi

Abū ʿAmr Muḥammad ibn ʿUmar ibn ʿAbd al-ʿAzīz al-Kashshī (Arabic: أَبُو عَمْرٍو مُحَمَّدٌ بْنُ عُمَرَ بْنِ عَبْدِ الْعَزِيزِ الْكَشَّيُّ ; Persian: محمد بن عمر بن عبد العزيز كشى ; d. around 951-2), known as al-Kashshi or (in Persian) as Kashshi, was a Persian Twelver Shi'ite scholar specializing in biographical evaluation (ʿilm al-rijāl) and hadith studies. He is the author of the Rijāl al-Kashshī, a major biographical work which ranks as one of the four main sources in the Shi'ite rijāl literature. Al-Kashshi's original work is now lost, but parts of it survive in an abridgement made by Shaykh Tusi (995–1067) called the Ikhtiyār maʿrifat al-rijāl.