Sunan Abi Dawud, Hadith 2652

Al Bara’ said “When the Prophet fought the polytheists in the battle of Hunain, they (the Muslims) retreated, he (the Prophet) came down from his mule and walked on foot.

حَدَّثَنَا عُثْمَانُ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا وَكِيعٌ، عَنْ إِسْرَائِيلَ، عَنْ أَبِي إِسْحَاقَ، عَنِ الْبَرَاءِ، قَالَ لَمَّا لَقِيَ النَّبِيُّ صلى الله عليه وسلم الْمُشْرِكِينَ يَوْمَ حُنَيْنٍ فَانْكَشَفُوا نَزَلَ عَنْ بَغْلَتِهِ فَتَرَجَّلَ ‏.‏

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also referenced under: Hadith 2658 (DarusSalam)