Musnad Ahmad 21:12

'Abd al-Razzaq narrated to us, Ma'mar narrated to us, from al-Zuhri, Kathir ibn 'Abbas ibn 'Abd al-Muttalib informed me, from his father al-'Abbas, who said: I witnessed Hunayn with the Messenger of Allah, may Allah bless him and grant him peace. He said: I saw the Prophet, may Allah bless him and grant him peace, and there was no one with him except me and Abu Sufyan ibn al-Harith ibn 'Abd al-Muttalib. We stayed with the Messenger of Allah, may Allah bless him and grant him peace, and did not depart from him, while he was upon a grey mule—and Ma'mar sometimes said: white—which Farwah ibn Nu'amah al-Judhami had gifted to him. When the Muslims and the disbelievers met, the Muslims turned away, retreating. The Messenger of Allah, may Allah bless him and grant him peace, began to urge his mule toward the disbelievers. Al-'Abbas said: I was holding the bridle of the mule of the Messenger of Allah, may Allah bless him and grant him peace, restraining it, while he was not sparing any effort to hasten toward the polytheists. Abu Sufyan ibn al-Harith was holding the stirrup of the Messenger of Allah, may Allah bless him and grant him peace. The Messenger of Allah, may Allah bless him and grant him peace, said: "O 'Abbas, call out: 'O companions of the Samurah [tree]!'" He said: I was a man with a loud voice, so I said at the top of my voice: "Where are the companions of the Samurah?" He said: By Allah, it was as if their turning back when they heard my voice was like the turning of cows toward their calves. They said: "Labbayk, Labbayk, Labbayk!" The Muslims advanced and fought the disbelievers. Then the Ansar called out, saying: "O company of Ansar!" Then the callers restricted it to the Banu al-Harith ibn al-Khazraj, and they called out: "O Banu al-Harith ibn al-Khazraj!" He said: The Messenger of Allah, may Allah bless him and grant him peace, looked—while he was on his mule, as if stretching over it—at their fighting, and the Messenger of Allah, may Allah bless him and grant him peace, said: "This is when the oven has heated up." He said: Then the Messenger of Allah, may Allah bless him and grant him peace, took some pebbles and threw them at the faces of the disbelievers, then said: "They are defeated, by the Lord of the Ka'bah! They are defeated, by the Lord of the Ka'bah!" He said: I went to look, and the fighting was in its state as I saw it. He said: By Allah, it was only that the Messenger of Allah, may Allah bless him and grant him peace, threw his pebbles at them, and I continued to see their sharpness blunted and their affair in retreat until Allah defeated them. He said: It is as if I am looking at the Prophet, may Allah bless him and grant him peace, urging his mule behind them.