What is the ruling on a son hitting his father and insulting his deceased mother, knowing that the father is abusive and the son is dutiful to his family, spends on them, and his father threatens him with death?

Striking, insulting, and cursing one's father are grave sins and destructive acts. Allah has forbidden even saying "uff" to a parent, so how much worse are striking, cursing, and insulting him? It is not permissible to belittle a father or describe him with negative attributes. Such belittling and disobedience are not justified by any shortcomings in upbringing or otherwise on the father's part during childhood, for Allah has commanded companionship with kindness even if the parent is a polytheist. Therefore, whoever strikes or curses his father must repent to Allah from this great sin, treat his father with kindness, and seek closeness to Allah through obeying him.