قَدْ كَانَ لَكُمْ آيَةٌ فِي فِئَتَيْنِ الْتَقَتَا ۖ فِئَةٌ تُقَاتِلُ فِي سَبِيلِ اللَّهِ وَأُخْرَىٰ كَافِرَةٌ يَرَوْنَهُم مِّثْلَيْهِمْ رَأْيَ الْعَيْنِ ۚ وَاللَّهُ يُؤَيِّدُ بِنَصْرِهِ مَن يَشَاءُ ۗ إِنَّ فِي ذَٰلِكَ لَعِبْرَةً لِّأُولِي الْأَبْصَارِ ١٣

There is certainly a sign for you in the two parties that encountered each other (in the battlefield of Badr)—one party (i.e., the Muslims) fought (a defensive war) in the cause of Allah, and the other comprised the disbelievers (i.e., the Meccan aggressors who invaded the peaceful Muslims of Medina). They saw them with their (own) eyes as twice their own number. And Allah provides strength with His reinforcement to whom He wills. In this incident, there is surely a (notable) lesson of warning for those who have eyes. (3:13)