What is the ruling on a wife secretly taking a small amount of money from her husband without his knowledge, claiming that he does not spend on her adequately, even though she lives with his family and all her needs are met?

It is not permissible for a wife to take anything from her husband's money without his permission, based on the Prophet's (peace be upon him) saying: "The wealth of a Muslim is not lawful except with his willing consent." The husband should also bestow gifts upon his wife, as the Prophet (peace be upon him) said: "Exchange gifts, and you will love one another."