Qur'an 3:166 · Aal-i-Imraan

وَمَآ أَصَٰبَكُمْ يَوْمَ ٱلْتَقَى ٱلْجَمْعَانِ فَبِإِذْنِ ٱللَّهِ وَلِيَعْلَمَ ٱلْمُؤْمِنِينَ

(166) And what struck you on the day the two armies met [at Uḥud] was by permission of Allāh that He might make evident the [true] believers