Sayyiduna Abu Rafi' (may Allah be pleased with him) said: "I saw the Messenger of Allah (peace and blessings be upon him) perform ablution washing each limb three times."
Al-Qa'nabi added in his narration: "And twice each, and once each as well."
Hadith Referenceالمعجم الكبير للطبراني / باب الألف / 933