﴿ فَإِذَا لَقِيتُمُ ٱلَّذِينَ كَفَرُوا۟ فَضَرْبَ ٱلرِّقَابِ حَتَّىٰٓ إِذَآ أَثْخَنتُمُوهُمْ فَشُدُّوا۟ ٱلْوَثَاقَ فَإِمَّا مَنًّۢا بَعْدُ وَإِمَّا فِدَآءً حَتَّىٰ تَضَعَ ٱلْحَرْبُ أَوْزَارَهَا ۚ ذَٰلِكَ وَلَوْ يَشَآءُ ٱللَّهُ لَٱنتَصَرَ مِنْهُمْ وَلَٰكِن لِّيَبْلُوَا۟ بَعْضَكُم بِبَعْضٍۢ ۗ وَٱلَّذِينَ قُتِلُوا۟ فِى سَبِيلِ ٱللَّهِ فَلَن يُضِلَّ أَعْمَٰلَهُمْ ﴾

“NOW WHEN you meet [in war] those who are bent on denying the truth, smite their necks until you overcome them fully, and then tighten their bonds; but thereafter [set them free,] either by an act of grace or against ransom, so that the burden of war may be lifted: thus [shall it be]. And [know that] had God so willed, He could indeed punish them [Himself]; but [He wills you to struggle] so as to test you [all] by means of one another. And as for those who are slain in God’s cause, never will He let their deeds go to waste:”

Please check ayah 47:9 for complete tafsir.