Surah Al-Anfal 8:15

يَـٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوٓا۟ إِذَا لَقِيتُمُ ٱلَّذِينَ كَفَرُوا۟ زَحْفًا فَلَا تُوَلُّوهُمُ ٱلْأَدْبَارَ

O you who have believed, when you meet those who disbelieve advancing [in battle], do not turn to them your backs [in flight].

Translation: Saheeh International

Tafsir

O you who believe when you encounter the disbelievers inching forward that is amassed advancing slowly because of their large numbers do not turn your backs to them fleeing.

Excerpt from Tafsir al-Jalalayn, commentary on 8:15, via Quran.com. The reader has the full commentary and 9 more tafsirs.