(24) باب الْوُضُوءِ ثَلاَثًا ثَلاَثًا
Narrated Humran:
(the slave of 'Uthman) I saw 'Uthman bin 'Affan asking for a tumbler
of water (and when it was brought) he poured water over his hands and
washed them thrice and then put his right hand in the water container
and rinsed his mouth, washed his nose by putting water in it and then
blowing it out. then he washed his face and forearms up to the
elbows thrice, passed his wet hands over his head and washed his feet
up to the ankles thrice. Then he said, "Allah's Messenger (ﷺ) said 'If
anyone performs ablution like that of mine and offers a two-rak'at
prayer during which he does not think of anything else (not related to
the present prayer) then his past sins will be forgiven.' "
Reference: Sahih al-Bukhari 159
In-book reference: Book 4, Hadith 25
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 1, Book 4, Hadith 161