Jami' al-Tirmidhi

Abu Hurairah narrated that : Allah's Messenger said: "When a Muslim, or believer, performs Wudu', washing his face, every evil that he looked at with his eyes leaves with the water - or with the last drop of water, or an expression similar to that - and when he washes his hands, every evil he did with his hands leaves with the water - or with the last drop of water - until he becomes free of sin."