Quran Ali 'Imran 3:165

Translation

Why [is it that] when a [single] disaster struck you [on the day of Uḥud], although you had struck [the enemy in the battle of Badr] with one twice as great, you said, "From where is this?" Say, "It is from yourselves [i.e., due to your sin]." Indeed, Allāh is over all things competent.