Is it permissible for a wife to take money from a joint savings box with her husband without his knowledge, in order to meet her private needs, knowing that this savings box contains money earned by both the wife and the husband?

A wife's salary is her exclusive right, and her husband has no claim to it unless he stipulated that she give him a portion of it in exchange for his permission for her to work, in which case she must fulfill this condition. If the husband is remiss in providing the obligatory maintenance, the wife may take what she needs from his money without his knowledge, or from their joint money. However, if the husband is providing maintenance appropriately and the wife desires more than the maintenance, she may only take from the joint money an amount equivalent to her share of it.