Surah Ali 'Imran 3:126

وَمَا جَعَلَهُ ٱللَّهُ إِلَّا بُشْرَىٰ لَكُمْ وَلِتَطْمَئِنَّ قُلُوبُكُم بِهِۦ ۗ وَمَا ٱلنَّصْرُ إِلَّا مِنْ عِندِ ٱللَّهِ ٱلْعَزِيزِ ٱلْحَكِيمِ

And Allāh made it not except as [a sign of] good tidings for you and to reassure your hearts thereby. And victory is not except from Allāh, the Exalted in Might, the Wise -

Translation: Saheeh International

Tafsir

What God ordained that is of reinforcement was only as a good tiding to you of victory and that your hearts might be at peace that they might be at rest and not be terrified by the large number of the enemy as compared to your small number. …

Excerpt from Tafsir al-Jalalayn, commentary on 3:126, via Quran.com. The reader has the full commentary and 9 more tafsirs.