Anas told of a man who came and said,“Messenger of God, I have done something which merits punishment, so appoint it for me.”He did not question him about it, and when the time for prayer came the man prayed along with him. Then when the Prophet had finished the prayer the man got up and said,“Messenger of God, I have done something which merits punishment, so appoint for me that God has decreed.”He asked,“Did you not pray along with us?”and when he replied that he had, he said,“Well, God has forgiven you your offence, or“your punishment”. (Bukhari and Muslim.)