Musnad Ahmad 760:0

It has been narrated from Abu Abdullah al-Sanabihi that he said: The Messenger of Allah (ﷺ) said: "When a servant of Allah performs wudu (ablution) and washes his face, every sin he committed with his face exits with the water—or with the last drop of water. When he washes his hands, every sin he committed with his hands exits with the water—or with the last drop of water. When he washes his feet, every sin he committed with his feet exits with the water—or with the last drop of water. Until he emerges purified from sins."