Narrated Abu Hurairah:
that the Prophet (ﷺ) said: "This Ayah was revealed about the people of Quba: In it are men who love to purify themselves. And Allah loves those who make themselves pure (9:108)." He said: "They used water to perform Istinja so this Ayah was revealed about them." (JA)
English reference (JA): Vol. 5, Book 44, Hadith 3100 (JA)
Arabic reference (JA): Book 47, Hadith 3383 (JA)