Narrated Abu Huraira: I heard Allah's Messenger, upon whom be peace, saying, "If there was a river at the door of anyone of you and he took a bath in it five times a day would you notice any dirt on him?" They said, "Not a trace of dirt would be left.” He said: "That is the parable of the five prayers, Allah wipes out sins with them.” (Sahih al-Bukhari 528)