Sunan At-Tirmidhi

Abdullah bin 'Amr narrated that :the Messenger of Allah said: ""It is among the greatest of sins that a man should curse his parents."" They said: ""O Messenger of Allah! Does a man curse his parents?"" He said: ""Yes. He verbally abuses the father of a man, who in turn, verbally abuses his father, and he (retaliates and) curses his mother , so he curses his mother