I heard Bara, and a man asked him, "Did you flee on the Day of Hunayn, Abu Umarah?"He replied, "No, by Allah, the Messenger of Allah ﷺ did not turn away. Rather, the young and lightly equipped men among his companions went out without armor or proper weapons, and they encountered a people of archers, the gathered forces of Hawazin and Banu Nasr, whose arrows hardly ever missed. They showered them with arrows that scarcely went astray. So they came back toward the Prophet ﷺ, who was on his white mule, with his cousin Abu Sufyan bin Harith bin Abdul-Muttalib leading it. He dismounted and prayed for victory, then said,'I am the Prophet, this is no lie, I am the son of Abdul-Muttalib.'Then he arranged his companions in ranks."
سمعت البراء، وسأله رجل: أكنتم فررتم يا أبا عمارة يوم حنين؟ قال: لا، والله ما ولى رسول الله ﷺ، ولكنه خرج شبان أصحابه وأخفاؤهم حسرا ليس بسلاح، فأتوا قوما رماة، جمع هوازن وبنى نصر، ما يكاد يسقط لهم سهم، فرشقوهم رشقا ما يكادون يخطئون، فأقبلوا هنالك إلى النبي ﷺ، وهو على بغلته البيضاء، وابن عمه أبو سفيان بن الحارث بن عبد المطلب يقود به، فنزل، واستنصر، ثم قال: أنا النبي لا كذب أنا ابن عبد المطلب ثم صف أصحابه.
Bukhari related it in "Jihad and Expeditions" (2930), and Muslim in "Jihad and Expeditions" (1776), both through the route of Abu Ishaq, who said, "..." and mentioned it, the wording being Bukhari's. Hunayn is a valley between Makkah and Taif.