Musnad Ahmad 3:20

Abu Kamil narrated to us, Ibrahim—meaning Ibn Sa'd—narrated to us, Ibn Shihab narrated to us, from 'Ata' ibn Yazid, from Humran, who said: 'Uthman called for water while he was on the seats. He poured it over his right hand and washed it. Then he inserted his right hand into the vessel and washed his palms three times. Then he washed his face three times, rinsed his mouth, and cleared his nose. He washed his forearms up to the elbows three times, then wiped his head, then washed his feet up to the ankles three times. Then he said: "I heard the Messenger of Allah, peace and blessings of Allah be upon him, say: 'Whoever performs ablution like this ablution of mine, then prays two rak'ahs in which he does not speak to himself, Allah will forgive him his preceding sins.'"