What is the ruling regarding a husband saying to his family about his wife, "She is my sister," and about his other wife, "She is only my wife," and what are the legal implications for the wife towards him?

We have previously clarified the ruling on a husband saying to his wife, "You are my sister." The husband must treat his wife well and kindly, and provide for her and their children. His provision for each wife should be sufficient for her needs. What a husband does by oppressing one wife to please another contradicts divine guidance. Each spouse must fulfill the rights of the other. If the husband withholds his wife's right, she may demand it through advice, arbitration, or judicial means. Some scholars have allowed a wife to withhold her husband's right if he is unjust to her, but generally, the harm in doing so outweighs its benefit.