(Go forth, light-armed and heavy-armed…) [9:41].
This was revealed about those who excused themselves from taking part in fighting because of their farms, work and preoccupations. But Allah, exalted is He, refused to excuse them unless they went forth to fight, despite of what had ensued from them before.
Muhammad ibn Ibrahim ibn Muhammad ibn Yahya informed us> Abu ‘Amr ibn Matar> Ibrahim ibn ‘Ali> Yahya ibn Yahya> Sufyan ibn ‘Uyaynah> Ibn Jad‘an [‘Ali ibn Zayd]> Anas who said: “Abu Talhah recited (Go forth, light-armed and heavy-armed) and then said: ‘I see that Allah has not excused anyone’, and he went to Syria to take part in Jihad and remained there until he died”. Said al-Suddi: “One day, al-Miqdad ibn al-Aswad, who was a huge, fat man, went to see the Messenger of Allah, Allah bless him and give him peace, to complain to him [about his size] and to dispense him from taking part in fighting. (Go forth, light-armed and heavy-armed) was revealed about him. But when this verse was revealed, people found it very hard on them, and so Allah, exalted is He, abrogated it and revealed instead (Not unto the weak nor unto the sick…) [9:91]”.
Asbab Al-Nuzul by Al-Wahidi , trans. Mokrane Guezzou