Sunan an-Nasa'i, Volume 3, Book 23, Hadith 2531 (DarusSalam) ⓘ

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."'[1]

أَخْبَرَنَا بِشْرُ بْنُ خَالِدٍ، قَالَ حَدَّثَنَا غُنْدَرٌ، عَنْ شُعْبَةَ، عَنْ سُلَيْمَانَ، عَنْ أَبِي وَائِلٍ، عَنْ أَبِي مَسْعُودٍ، قَالَ لَمَّا أَمَرَنَا رَسُولُ اللَّهِ صلى الله عليه وسلم بِالصَّدَقَةِ فَتَصَدَّقَ أَبُو عَقِيلٍ بِنِصْفِ صَاعٍ وَجَاءَ إِنْسَانٌ بِشَىْءٍ أَكْثَرَ مِنْهُ فَقَالَ الْمُنَافِقُونَ إِنَّ اللَّهَ عَزَّ وَجَلَّ لَغَنِيٌّ عَنْ صَدَقَةِ هَذَا وَمَا فَعَلَ هَذَا الآخَرُ إِلاَّ رِيَاءً فَنَزَلَتِ ‏{‏ الَّذِينَ يَلْمِزُونَ الْمُطَّوِّعِينَ مِنَ الْمُؤْمِنِينَ فِي الصَّدَقَاتِ وَالَّذِينَ لاَ يَجِدُونَ إِلاَّ جُهْدَهُمْ ‏}‏ ‏.‏