The Prophet ﷺ said: The following verse was revealed in connection with the people of Quba': "In it are men who love to be purified" (ix.108). He (AbuHurayrah) said: They used to cleanse themselves with water after easing. So the verse was revealed in connection with them. (Using translation from Abū Dāʾūd 44)
عَنِ النَّبِيِّ ﷺ قَالَ نَزَلَتْ هَذِهِ الْآيَةُ فِي أَهْلِ قُبَاءَ {فِيهِ رِجَالٌ يُحِبُّونَ أَنْ يَتَطَهَّرُوا} [التوبة 108] قَالَ كَانُوا يَسْتَنْجُونَ بِالْمَاءِ فَنَزَلَتْ فِيهِمْ هَذِهِ الْآيَةُ