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.