3:166

وَمَٓا اَصَابَكُمْ یَوْمَ الْتَقَى الْجَمْعَانِ فَبِاِذْنِ اللّٰهِ وَلِیَعْلَمَ الْمُؤْمِنٖینَۙ

Wama asabakum yawma iltaqa aljamAAani fabiithni Allahi waliyaAAlama almumineena

Translations

And what struck you on the day the two armies met was by permission of Allah that He might make evident the [true] believers

Saheeh International

That which befell you, on the day when the two armies met, was by permission of Allah; that He might know the true believers

Marmaduke Pickthall