One day Sayyiduna Uthman bin Affan (may Allah be pleased with him) called for water and performed ablution. He washed his palms three times, then rinsed his mouth and cleaned his nose three times, then washed his face three times, then washed his right arm up to and including the elbow three times, then washed the left in the same way, then wiped his head, then washed his right foot up to and including the ankles three times, then washed the left foot in the same way. Then he said: One day I saw the Messenger of Allah (peace and blessings be upon him) performing ablution in this way, and then the Messenger of Allah (peace and blessings be upon him) said: "Whoever performs ablution like this ablution of mine, then stands and prays two rak'ahs in which he does not let his mind wander to any thought, his past sins will be forgiven."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 318