(And when thou settedst forth at daybreak from thy housefolk…) [3:121].
This was revealed about the Battle of Uhud.
Sa'id ibn Muhammad al-Zahid informed us> Abu 'Ali al-Faqih> Abu'l-Qasim al-Baghawi> Yahya ibn 'Abd al-Hamid al-Hammani> 'Abd Allah ibn Ja'far al-Makhrami> Ibn 'Awn> al-Miswar ibn Makhramah who said: “I said to 'Abd al-Rahman ibn 'Awf: 'Uncle, tell me about what happened to you at Uhud?' He said: 'Read the first one hundred and twenty verses of Al 'Imran you will find your answer: (And when thou settedst forth at daybreak from thy housefolk) up to His saying (Then, after grief, He sent down security for you…) [3:154]' ”.
Asbab Al-Nuzul by Al-Wahidi , trans. Mokrane Guezzou