(And was it so, when a disaster smote you…) [3:165].
Said Ibn 'Abbas: “'Umar ibn al-Khattab related to me, saying: 'The following year at the Battle of Uhud, they were punished for taking ransom in exchange for releasing the prisoners of the disbelievers. Seventy among them were killed, the Companion of the Messenger of Allah, Allah bless him and give him peace, fled from fighting and his molar was broken and his skull smashed to the extent that blood flowed over his face. Allah, exalted is He, then revealed (And was it so, when a disaster smote you) up to His saying (It is from yourselves…). He said: Because of the ransom you took'
Asbab Al-Nuzul by Al-Wahidi , trans. Mokrane Guezzou