إِذْ يُوحِى رَبُّكَ إِلَى ٱلْمَلَـٰٓئِكَةِ أَنِّى مَعَكُمْ فَثَبِّتُوا۟ ٱلَّذِينَ ءَامَنُوا۟ ۚ سَأُلْقِى فِى قُلُوبِ ٱلَّذِينَ كَفَرُوا۟ ٱلرُّعْبَ فَٱضْرِبُوا۟ فَوْقَ ٱلْأَعْنَاقِ وَٱضْرِبُوا۟ مِنْهُمْ كُلَّ بَنَانٍۢ
“[Remember] when your Lord inspired to the angels, "I am with you, so strengthen those who have believed. I will cast terror into the hearts of those who disbelieved, so strike [them] upon the necks and strike from them every fingertip."”
Allah instructing the angels to strengthen the believers at Badr.
Surah al-Anfal was revealed on the plains of Badr regarding the battle and its aftermath.