وَمَا أَصَابَكُمْ يَوْمَ الْتَقَى الْجَمْعَانِ فَبِإِذْنِ اللَّهِ وَلِيَعْلَمَ الْمُؤْمِنِينَ
“So what you suffered on the day the two armies met was by Allah's Will, so that He might distinguish the [true] believers”
On the trial of the two armies meeting at Uhud.