What is the ruling of Islamic law regarding a husband who does not provide for his wife and takes her money despite his affluence?

There is no doubt that clothing is an obligatory expense for the husband towards his wife, to be provided in a reasonable manner, based on the saying of the Messenger of Allah (peace be upon him): "...Verily, their right upon you is that you treat them well in their clothing and their food."

As for medical expenses, most scholars are of the opinion that a man is not obliged to bear his wife's medical expenses. However, it is a sign of good companionship for a man to spend on his wife's treatment to the best of his ability.

And for a husband to seize his wife's money by force is clear oppression and impermissible.

The wife is advised to gently advise her husband and ask him to spend on her in a reasonable manner, reminding him that the reward for spending on one's family is among the greatest rewards, based on the saying of the Messenger of Allah (peace be upon him): "A dinar you spend in the way of Allah... and a dinar you spend on your family, the greatest in reward is that which you spend on your family."

If he does not heed the advice and withholds her obligatory sustenance, she is permitted to take from his money what suffices her in a reasonable manner without his knowledge. If that does not work, she may refer his case to the Sharia judge to compel him to provide the obligatory sustenance, or seek divorce if he refuses.