Humran, the freed slave of Sayyiduna Uthman (may Allah be pleased with him), reported that he saw Sayyiduna Uthman bin Affan (may Allah be pleased with him): he called for a vessel, poured water onto his hands three times and washed them, then put his hand into the vessel and rinsed his mouth, blew his nose, and washed his face three times, then washed his hands up to and including the elbows three times, then wiped his head, then washed his feet up to and including the ankles three times. Then he said that the Messenger of Allah (peace and blessings be upon him) said: "Whoever performs ablution like my ablution, then prays two rak'ahs in which he does not let any thought arise within himself, his past sins will be forgiven."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 244