The Prophet (may Allah's peace & blessings be upon him, his family & companions) said: 'If one of you had a stream running at his door and he bathed in it five times every day, do you think any dirt would be left on him?' His Companions answered, 'No dirt at all would be left on him!' He said, 'That is what the five (daily) prayers are like, with which Allah washes away your sins'. (Bukhari)