Surah Ali 'Imran 3:160

إِن يَنصُرْكُمُ ٱللَّهُ فَلَا غَالِبَ لَكُمْ ۖ وَإِن يَخْذُلْكُمْ فَمَن ذَا ٱلَّذِى يَنصُرُكُم مِّنۢ بَعْدِهِۦ ۗ وَعَلَى ٱللَّهِ فَلْيَتَوَكَّلِ ٱلْمُؤْمِنُونَ

If Allāh should aid you, no one can overcome you; but if He should forsake you, who is there that can aid you after Him? And upon Allāh let the believers rely.

Translation: Saheeh International

Tafsir

If God helps you if He gives you assistance against your enemy as on the Day of Badr then none can overcome you; but if He forsakes you if He refrains from assisting you as on the Day of Uhud then who is there who can help you after Him? that is after His forsaking you? In other words there is no one to help you. …

Excerpt from Tafsir al-Jalalayn, commentary on 3:160, via Quran.com. The reader has the full commentary and 9 more tafsirs.