Humran said: I saw Sayyiduna Uthman bin Affan (may Allah be pleased with him) performing ablution. He washed his hands three times, washed his face and his forearms three times each, wiped his head three times and washed his feet three times. Then he said: This is how I saw the Messenger of Allah (peace and blessings be upon him) perform ablution, and he (peace and blessings be upon him) said: "Whoever performs ablution less than this ablution of mine, it will suffice him."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 293