It is narrated from Sayyiduna ‘Uwain bin Sa‘idah Ansari ‘Ajlani (may Allah be pleased with him) that the Noble Prophet (peace and blessings of Allah be upon him) said to the people of Quba:“Indeed, Allah Almighty has praised you greatly regarding purity.”Then he recited this verse «‏‏‏‏فِيهِ رِجَالٌ يُحِبُّونَ أَن يَتَطَهَّرُوا ۚ وَاللَّهُ يُحِبُّ الْمُطَّهِّرِينَ» ‏‏‏‏ [ سورة التوبة ] “In it are men who love to purify themselves, and Allah loves those who purify themselves.”Then the Prophet (peace and blessings of Allah be upon him) asked them:“What is that purity? (for which Allah Almighty has praised you so much)”They replied: We do not know of anything except that there were some Jews who were our neighbors, and they used to wash their backsides after relieving themselves, so we also started washing our backsides (while performing istinja) as they used to wash.