Is it permissible to withhold money from the father to stop his harmful actions, which include harming the mother, communicating with a foreign maid, consuming sexual stimulants, and frequently being absent from the home?

Your duty towards this father is to advise him, and to try to keep him away from forbidden matters by finding him a suitable job, and not leaving him with idleness. You should also direct preachers and scholars to him to advise and guide him, while verifying the truth of his relationship with the woman. It is not permissible to cut off his allowance if he is in need, nor is it permissible to prevent him from what he spends on unlawful things. Rather, he should be advised and guided, and kept busy with what consumes his effort and thought, or married to someone he loves if he wishes to marry.