Advice regarding undutifulness to parents

Q: I have a son who is over twenty years old and is studying at the university. He is always quarreling with his mother on the grounds that she raises her voice at his siblings in the house. He now does not greet her, and he has boycotted her for two months. Even now, he enters the house and eats, drinks, and sleeps, but he never greets her. What is my position regarding him, considering that I am his father? I have advised him, but he has repeatedly and repeatedly refused, and he remains stubborn in his blindness. Please inform us, may Allah reward you with good?

A: This is a compound ignoramus. He has committed a great evil and major undutifulness to parents. We ask Allah for guidance for us and for him. It is obligatory to warn him of this and to prevent him from this undutifulness, even by beating him, or by expelling him from the house entirely, or by other suitable forms of discipline, if words are of no avail in his case. There is no harm in referring his case to the committee or the court if his father is unable to resolve the matter. May Allah rectify him, inspire him with sound judgment, and protect him from the evil of his own self.