It was narrated that Abu Hurairah said:"The Messenger of Allah said: 'The (following) was revealed about the people of Quba': 'In it (the mosque) are men who love to clean and purify themselves. And Allah loves those who make themselves clean and pure.'" He said: 'They used to clean themselves with water (after urinating), and this Verse was revealed concerning them.'"
حَدَّثَنَا أَبُو كُرَيْبٍ، حَدَّثَنَا مُعَاوِيَةُ بْنُ هِشَامٍ، عَنْ يُونُسَ بْنِ الْحَارِثِ، عَنْ إِبْرَاهِيمَ بْنِ أَبِي مَيْمُونَةَ، عَنْ أَبِي صَالِحٍ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ " نَزَلَتْ فِي أَهْلِ قُبَاءٍ {فِيهِ رِجَالٌ يُحِبُّونَ أَنْ يَتَطَهَّرُوا وَاللَّهُ يُحِبُّ الْمُطَّهِّرِينَ} قَالَ كَانُوا يَسْتَنْجُونَ بِالْمَاءِ فَنَزَلَتْ فِيهِمْ هَذِهِ الآيَةُ " .
IbnMaja
The Book of Purification and its Sunnah • Hadith 357