Majma al-Zawaid — Hadith 1164

It is reported about Sayyiduna Uthman (may Allah be pleased with him) that he called for water for ablution, rinsed his mouth, put water into his nose, washed his face three times, washed both his arms three times, wiped his head, washed his feet, and then laughed. He said: Will you not ask me why I laughed? We said: O Commander of the Believers, why did you laugh? He said: The reason I laughed is that once the Prophet (peace and blessings be upon him) called for water for ablution near this place, and he performed ablution just as I have performed it. Then he (peace and blessings be upon him) laughed just as I laughed, and then he (peace and blessings be upon him) said: Will you not ask me why I laughed? We said: O Prophet of Allah, what made you laugh? He (peace and blessings be upon him) said: I laughed because when a servant performs ablution and washes his face, Allah Almighty removes from him every sin he committed with his face; when he washes his arms, the same happens; when he wipes his head, the same happens; and when he washes his feet, the same happens.
Al-Bazzar recorded it, and its narrators are the narrators of the Sahih; it is also in the Sahih in abridged form.