(And whosoever keepeth his duty to Allah, Allah will appoint a way out for him, And will provide for him from (a quarter) whence he hath no expectation) [65:3].
This verse was revealed about 'Awf ibn Malik al-Ashja'i whose son was imprisoned by the idolaters. He went to the Messenger of Allah, Allah bless him and give him peace, and complained to him about his poverty, saying: “The enemy has imprisoned my son and his mother is very distressed, what do you advise me to do?” The Prophet, Allah bless him and give him peace, said to him: “Be fearful of Allah and be patient. I also command you and your wife to often repeat 'there is no strength or might except by Allah' ”. So he went home and said to his wife: “The Messenger of Allah, Allah bless him and give him peace, commanded both of us to often repeat 'there is no strength or might except by Allah' ”. She said: “How good is that with which he has commanded us!” And they both started saying it straightaway. It happened that the enemy became distracted from their son and the latter led their sheep away and fled. He brought these sheep to his father; they were four thousand heads. This verse was revealed about this incident.
'Abd al-'Aziz ibn 'Abdan informed us> Muhammad ibn 'Abd Allah ibn Nu'aym> Abu'l-Qasim al-Hasan ibn Muhammad ibn al-Husayn al-Sakuni> 'Ubayd ibn Kathir al-'Amiri> 'Abbad ibn Ya'qub> Yahya ibn Adam> Isra'il> 'Ammar ibn Mu'awiyah> Salim ibn Abi al-Ja'd> Jabir ibn 'Abd Allah who said: “This verse (And whosoever keepeth his duty to Allah, Allah will appoint a way out for him, And will provide for him from (a quarter) whence he hath no expectation) was revealed about a man from Ashja'. This man was poor but had numerous children. He went to the Messenger of Allah, Allah bless him and give him peace, and asked him for help. The Prophet, Allah bless him and give him peace, told him: 'Fear Allah and be patient!' The man went back to his companions and when they asked him about what the Prophet had given him, he said: 'He did not give me anything; he simply said: Fear Allah and be patient'. Not long after this, a son of this man, who had been captured by the enemy, brought him sheep. The man went to the Messenger of Allah, Allah bless him and give him peace, to ask him about what he should do with the sheep, and told him the full story. The Messenger of Allah, Allah bless him and give him peace, said to him: 'Keep them, they are yours' ”.
Asbab Al-Nuzul by Al-Wahidi , trans. Mokrane Guezzou