Hadithcore
Sunan Abi Dawud, 2648
sahih· Al-Albani

Abu Sa’id said “The verse “If any do turn his back to them on such a day” was revealed on the day of the Battle of Badr.”

حَدَّثَنَا مُحَمَّدُ بْنُ هِشَامٍ الْمِصْرِيُّ، حَدَّثَنَا بِشْرُ بْنُ الْمُفَضَّلِ، حَدَّثَنَا دَاوُدُ، عَنْ أَبِي نَضْرَةَ، عَنْ أَبِي سَعِيدٍ، قَالَ نَزَلَتْ فِي يَوْمِ بَدْرٍ ‏{‏ وَمَنْ يُوَلِّهِمْ يَوْمَئِذٍ دُبُرَهُ ‏}‏ ‏.‏

References2 variants
In-Book Reference
Book 15, Hadith 172
English Reference
Book 14, Hadith 2642