Musnad Ahmad 1007:123

'Affan narrated to us, Hammad ibn Salamah narrated to us, Abu Muhammad ibn Ma'bad ibn Abi Qatadah informed us, from the son of Ka'b ibn Malik, who said: Abu Qatadah came out to us while we were saying: "The Messenger of Allah, peace and blessings of Allah be upon him, said such and such, and the Messenger of Allah, peace and blessings of Allah be upon him, said such and such." He said: "May the faces be disfigured! Do you know what you are saying? I heard the Messenger of Allah, peace and blessings of Allah be upon him, say: 'Whoever says about me what I have not said, let him take his seat in the Fire.'" 'Affan said: And Muhammad ibn Ka'b said to me...