What is the ruling on a Muslim wife disposing of her husband's money without his knowledge, and what should the husband do if he discovers that?

A woman is not permitted to dispose of her husband's property except with his permission. However, if he withholds her right to maintenance, she may take from his wealth an amount sufficient for her maintenance, according to what is customary (bil-ma'ruf). This is based on the saying of the Prophet (peace be upon him) to Hind bint Utbah: "Take what suffices you and your child, in a reasonable manner." If she takes more than her maintenance without his permission, her husband has the choice to either waive this right or demand it back from her. It is preferable for him to pardon and forgive, for Allah Almighty says: "And do not forget graciousness between you."