Muhammad bin Abd Allah bin Quhzādh, from the people of Marw, narrated to me, he said Alī bin Husayn bin Wāqid informed me, he said Abd Allah bin al-Mubārak said, I said to Sufyān ath-Thawrī: ‘Indeed Abbād bin Kathīr, about whose condition you are aware, when he related said: ‘So when I was in an assembly and Abbād was mentioned there, I praised him regarding his Dīn and said: ‘Do not take from him.’ Muhammad said, Abd Allah bin Uthmān narrated to us, he said, my father said, Abd Allah bin al-Mubārak said: ‘I ended up in an assembly of Shu’bah, and he said: ‘This is Abbād bin Kathīr so be warned against him.’
Sahih Muslim · Introduction