What is the ruling on one who curses himself?

It is forbidden for a Muslim to curse himself or others, for cursing is expulsion from the mercy of Allah. The Prophet forbade supplicating against oneself except with good. Scholars have agreed on the prohibition of cursing. An exception to this is a man cursing himself in li'an (oath of condemnation) if he accuses his wife (of adultery) and is truthful, or in an oath if he is truthful in his statement, "If I did such and such, then the curse of Allah be upon me," or similar phrases.