How can one deal with parents who mistreat their son, where the father constantly insults him and gets angry at him because he prevented him from traveling out of concern for his health after surgery, while the mother considers him as good as dead because his wife lives with him abroad?

Allah has mandated righteousness towards parents and benevolence towards them, even if they are abusive. However, it is not permissible for a father to abuse his child. Regarding a wife's travel with her husband, it is a right for the wife, and no one can prevent her from it. The husband should not be absent from his wife for more than six months unless she consents. If the husband or his wife fears falling into sin before this period, he must bring her. Obedience to parents is not obligatory if it leads to disobedience to the Creator, but it is recommended to treat them gently and not cease visiting them.