Abd al-Rahman ibn Mahdi

Abu Sa'id Abd al-Rahman ibn Mahdi al-'Anbari al-Basri was one of the greatest hadith scholars of his era. He studied under Sufyan al-Thawri, Sufyan ibn 'Uyaynah, and Malik ibn Anas. Imam al-Shafi'i wrote his famous Risalah (the first work on Islamic jurisprudential theory) as a response to a request by Ibn Mahdi. Ahmad ibn Hanbal ranked him alongside Yahya al-Qattan as the two greatest hadith critics of their time. He died in Basra in 198 AH.