3:166
وَمَآ أَصَـٰبَكُمْ يَوْمَ ٱلْتَقَى ٱلْجَمْعَانِ فَبِإِذْنِ ٱللَّهِ وَلِيَعْلَمَ ٱلْمُؤْمِنِينَ
wamā aṣābakum yawma l-taqā l-jamʿāni fabi-idh'ni l-lahi waliyaʿlama l-mu'minīna
what befell you on the day the two armies met in battle happened with God’s permission and in order for Him to see who were the true believers and who were the hypocrites who,
And what you suffered (of the disaster) on the day (of the battle of Uhud when) the two armies met, was by the leave of Allâh, in order that He might test the believers.