Musnad Ahmad 25:1328

'Abd al-Rahman ibn Mahdi narrated to us, 'Ikrimah ibn 'Ammar narrated to us, he said: Abu Zumayl narrated to me, he said: 'Abdullah ibn 'Abbas narrated to me, he said: When the Haruriyyah (Kharijites) emerged, they withdrew, so I said to them: "The Messenger of Allah, peace and blessings of Allah be upon him, made a peace treaty with the polytheists on the day of Hudaybiyyah. He said to 'Ali: 'Write, O 'Ali: This is what Muhammad, the Messenger of Allah, has agreed upon.' They said: 'If we knew that you were the Messenger of Allah, we would not have fought you.' The Messenger of Allah, peace and blessings of Allah be upon him, said: 'Erase it, O 'Ali. O Allah, You know that I am Your Messenger. Erase it, O 'Ali, and write: This is what Muhammad ibn 'Abdullah has agreed upon.' By Allah, the Messenger of Allah is better than 'Ali, and he erased his own name, and that erasure did not erase him from Prophethood. Have I refuted this [objection] of yours?" They said: "Yes."