Surah Ali 'Imran 3:13

قَدْ كَانَ لَكُمْ ءَايَةٌ فِى فِئَتَيْنِ ٱلْتَقَتَا ۖ فِئَةٌ تُقَـٰتِلُ فِى سَبِيلِ ٱللَّهِ وَأُخْرَىٰ كَافِرَةٌ يَرَوْنَهُم مِّثْلَيْهِمْ رَأْىَ ٱلْعَيْنِ ۚ وَٱللَّهُ يُؤَيِّدُ بِنَصْرِهِۦ مَن يَشَآءُ ۗ إِنَّ فِى ذَٰلِكَ لَعِبْرَةً لِّأُو۟لِى ٱلْأَبْصَـٰرِ

Already there has been for you a sign in the two armies which met [in combat at Badr] - one fighting in the cause of Allāh and another of disbelievers. They saw them [to be] twice their [own] number by [their] eyesight. But Allāh supports with His victory whom He wills. Indeed in that is a lesson for those of vision.

Translation: Saheeh International

Tafsir

There has already been a sign an example the verb qad kāna ‘there has been’ is used to separate the statement to follow from the previous one for you in two hosts two parties that met one another in battle on the day of Badr; …

Excerpt from Tafsir al-Jalalayn, commentary on 3:13, via Quran.com. The reader has the full commentary and 9 more tafsirs.