3:166

The misfortune which befell you when the two armies met in the battle of Uhud was with the leave of Allah, so that He might know the true believers
Meaning:-
Uhud: Uhud: Battle of Uhud (Arabic: ‘Uḥud) was fought on Saturday, March 19, 625 (3 Shawwal 3 AH in the Islamic calendar) at the valley located in front of Mount Uhud, in what is now northwestern Arabia.