Is it permissible for a husband to be stingy with his wife and children regarding their financial support and give his money to others, and is it permissible for the wife not to help her husband with household expenses, especially given that his salary is three times hers?

The Sharia obligates the husband to provide for his wife and children. If the husband is stingy and fails to fulfill his duty of maintenance, his wife is permitted to take from his money the customary amount that suffices her and her children, even without his knowledge. It is commendable for the husband to give gifts to his wife, just as it is appropriate for the wife to give gifts to her husband as long as she is able. It is not obligatory for the wife to spend on herself and her children, even if she is wealthy; if she refrains from doing so, she is not sinful. However, if her refraining from spending might lead to an escalation of problems between her and her husband, it is preferable for her not to stop spending.