Allah's Messenger, may the peace and blessings of Allah be upon him, said thrice, "Shall I not inform you of the most destructive sins?" We said, "Yes, O Allah's Messenger" He said, "To join partners in worship with Allah: to be undutiful to one's parents." The Prophet, may the peace and blessings of Allah be upon him, said thrice, sat up after he had been reclining and added, "And I warn you against giving forged statement and a false witness; I warn you against giving a forged statement and a false witness." The Prophet kept on saying that warning till we thought that he would not stop.