حَدَّثَنِي بِشْرُ بْنُ خَالِدٍ أَبُو مُحَمَّدٍ، أَخْبَرَنَا مُحَمَّدُ بْنُ جَعْفَرٍ، عَنْ شُعْبَةَ، عَنْ سُلَيْمَانَ، عَنْ أَبِي وَائِلٍ، عَنْ أَبِي مَسْعُودٍ، قَالَ لَمَّا أُمِرْنَا بِالصَّدَقَةِ كُنَّا نَتَحَامَلُ فَجَاءَ أَبُو عَقِيلٍ بِنِصْفِ صَاعٍ، وَجَاءَ إِنْسَانٌ بِأَكْثَرَ مِنْهُ، فَقَالَ الْمُنَافِقُونَ إِنَّ اللَّهَ لَغَنِيٌّ عَنْ صَدَقَةِ هَذَا، وَمَا فَعَلَ هَذَا الآخَرُ إِلاَّ رِئَاءً‏.‏ فَنَزَلَتْ ‏ End hadith 4‏ الآيَةَ‏.‏

Narrated Abu Mas`ud: When we were ordered to give alms, we began to work as porters (to earn something we could give in charity). Abu `Aqil came with one half of a Sa` (special measure for food grains) and another person brought more than he did. So the hypocrites said, "Allah is not in need of the alms of this (i.e. Abu `Aqil); and this other person did not give alms but for showing off." Then Allah revealed:-- 'Those who criticize such of the Believers who give charity voluntarily and those who could not find to give in charity except what is available to them.' (9.79) Translation Not Available

Book Ref: Sahih Bukhari Book 65 Hadith 4668
Web Ref:  Sahih Bukhari Vol 6 Book 60 Hadith 190