(Those who point at such of the believers as give the alms willingly…) [9:79].
Sa'id ibn Muhammad ibn Ahmad ibn Ja'far informed us> Abu 'Ali al-Faqih> Abu 'Ali Muhammad ibn Sulayman al-Maliki> Abu Musa Muhammad ibn al-Muthanna> Abu'l-Nu'man al-Hakam ibn 'Abd Allah al-'Ijli> Shu'bah> Salman> Abu Wa'il> Abu Mas'ud who said: “When the verses of alms were revealed, we used to ask to carry people stuff in exchange for a wage so that we could earn and pay alms from what we had earned. A man came and gave a lot for alms, some people commented: 'He is just showing off'. Another man came and gave a measure (sa') for alms, and they commented: 'Allah can do without the measure of this man', and so Allah revealed (Those who point at such of the believers as give the alms willingly and such as can find naught to give but their endeavours…)”. This is narrated by Bukhari from Abu Qudamah 'Ubayd Allah ibn Sa'id>> Abu Nu'man.
Qatadah and others said: “The Messenger of Allah, Allah bless him and give him peace, encouraged people to give alms. 'Abd al-Rahman ibn 'Awf took with him four thousand silver coins and said: 'O Messenger of Allah, all my wealth consists of eight thousand silver coins, I have kept half of it for my dependents and brought the other half for you to spend it in the way of Allah'. The Messenger of Allah, Allah bless him and give him peace, said: 'may Allah bless you for that which you have given and for that which you have withheld'. Allah did indeed bless the wealth of 'Abd al-Rahman to the extent that when he died he was survived by two wives who inherited one eighth of his fortune. This one eighth was estimated at 160 thousand silver coins. On the same day, 'Asim ibn 'Adiyy ibn al-'Ajlan gave to charity one hundred wasq of dates while Abu 'Aqil al-Ansari gave one sa' of dates. Abu 'Aqil said: 'O Messenger of Allah, I spent the night drawing water with a rope until I earned two measures (sa') of dates; I kept one for my family and brought the other'. The Messenger of Allah, Allah bless him and give him peace, commanded him to spread it among the received alms. The hypocrites defamed 'Abd al-Rahman and 'Asim, saying ''Abd al-Rahman and 'Asim gave alms only to show off. Allah and His Messenger can indeed do without the measure (sa') of Abu 'Aqil; he only wished to appear righteous'. And so Allah, exalted is He, revealed this verse”.
Asbab Al-Nuzul by Al-Wahidi , trans. Mokrane Guezzou