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." (FR)
English reference (FR): Vol. 5, Book 44, Hadith 3100 (FR)
Arabic reference (FR): Book 47, Hadith 3383 (FR)