Bara bin Azib reported,
A man from Qays asked Bara, "Did you flee from the Messenger of Allah ﷺ on the day of Hunayn?"Bara replied, "But the Messenger of Allah ﷺ did not flee. The tribe of Hawazin that day were skilled archers. When we charged at them, they scattered, so we rushed upon the spoils, but then they met us with a barrage of arrows. I saw the Messenger of Allah ﷺ on his white mule, with Abu Sufyan bin Harith holding its bridle, while he was saying, 'I am the Prophet, this is no lie. I am the son of Abdul-Muttalib.'"In another narration, "As for me, I bear witness about the Prophet ﷺ that he did not turn away, but the swift ones among the people rushed ahead, and Hawazin showered them with arrows."
Azami 9214
Sahihعن البراء بن عازب
وسأله رجل من قيس: أفررتم عن رسول الله ﷺ يوم حنين؟ فقال البراء: ولكن رسول الله ﷺ لم يفر، و كانت هوازن يومئذ رماة، وإنا لما حملنا عليهم انكشفوا، فأكببنا على الغنائم فاستقبلونا بالسهام، ولقد رأيت رسول الله ﷺ على بغلته البيضاء، وإن أبا سفيان بن الحارث آخذ بلجامها وهو يقول: أنا النبي لا كذب أنا ابن عبد المطلب. وفي رواية: أما أنا أشهد على النبي ﷺ أنه لم يول، ولكن عجل سرعان القوم فرشقتهم هوازن.
Bukhari narrated it in the Battles chapter (4317), and Muslim narrated it in Jihad and Expeditions (1776: 80), both from Muhammad bin Bashshar, who said, Muhammad bin Jafar Ghundar narrated to us, Shubah narrated to us from Abu Ishaq, who said, I heard Bara, and a man from Qays asked him, and he mentioned it.This was a magnificent stance from the Prophet ﷺ, showing his trust in Allah 
and his reliance upon Him, riding a mule that was not fast in its gait, driving it forward toward the faces of the enemy. This is the greatest proof of his prophethood ﷺ. So Allah the Exalted sent down what He said, "Then Allah sent down His tranquility upon His Messenger and upon the believers, and sent down soldiers whom you did not see" [Tawbah 9:26]. As for His saying, "and sent down soldiers whom you did not see", the soldiers are the angels.