It was narrated that Abu Mas 'ud said:"When the Messenger of Allah commanded us to give in charity, Abu 'Aqil give half a Sa', and another man brought much more than that. The hypocrites said: 'Allah has no need of the charity of the former, and the latter only did it to show off. Then the following was revealed: 'Those who defame such of the believers who give charity voluntarily, and such who could not find to give charity except what is available to them

English translation · Sunan an-Nasa'i