Is it permissible for a wife to save money from her husband's wealth without his knowledge, and refuse to answer him when he asks about her expenditures?

A wife is not permitted to dispose of her husband's money without his permission. The husband must send sufficient maintenance (nafaqah) to his wife, and he is not obligated to send more than that. It is advised that the husband does not question his wife about her expenditures if she dislikes it. The wife must treat her husband kindly, and good faith should prevail between the spouses. If the wife saves some of the obligatory maintenance or some of the additional money willingly sent by her husband, there is no harm in that, because it becomes her own money. A wife's refusal to travel to her husband constitutes disobedience (nushuz), which forfeits her maintenance, unless she stipulated this condition in the marriage contract.