What is the ruling on dealing with an oppressive father who abuses his wife and children with beating, cursing, and false accusations, takes his children's money, refuses to spend on his family, and hinders his son's marriage, knowing that the children suffer psychologically because of this?

Filial piety is one of the greatest acts of obedience, and disobeying one's parents is one of the gravest sins. You must be patient with your father and be good to him, even if he wrongs you or is a polytheist inviting to polytheism. You should offer him advice in a good manner.

Your father's actions, such as hitting your mother, abandoning financial support, and slandering your sisters, are impermissible. You should treat him like a sick person, draw closer to him with gifts, and kiss his head and hand.

It is also advisable to involve righteous people to advise him if you believe their advice will be effective. Increase your supplications for his guidance and righteousness, for Allah will help you in your devotion to him.