Musannaf Ibn Abi Shaybah

Hazrat Suwaid bin Ghaflah (may Allah have mercy on him) narrates that Hazrat Ali (may Allah be pleased with him) burned the heretics in the marketplace. When fire was thrown upon them, he (may Allah be pleased with him) said: "Allah and His Messenger have spoken the truth." Then he (may Allah be pleased with him) turned back, and I followed behind him. He (may Allah be pleased with him) turned towards me and asked: "Are you Suwaid?" I said: "Yes!" I submitted: "O Commander of the Faithful! I heard that you were saying something?" He (may Allah be pleased with him) said: "O Suwaid! Indeed, I am with ignorant people. When you hear that I am saying something, then know that it is what the Messenger of Allah (peace and blessings be upon him) has said, and it is absolutely true."