Hadith 1042

Abu Hurairahu (May Allah be pleased with him) reported: I heard the Messenger of Allah (PBUH) saying, "Say, if there were a river at the door of one of you in which he takes a bath five times a day, would any soiling remain on him?" They replied, "No soiling would left on him." He (PBUH) said, " That is the five (obligatory) Salat (prayers). Allah obliterates all sins as a result of performing them."

[Al-Bukhari and Muslim].