Does divorce take effect if the wife does not inform her husband of her knowledge of his sister's relationship with a young man, knowing that the husband swore to divorce her if she knew anything about it and did not inform him, and is she obligated to inform him despite his sister's knowledge of the oath and her desire not to harm her?

Swearing by divorce is subject to the ruling of conditional divorce. If the wife performs the action sworn upon, the divorce takes effect. If the husband does not specify a time for informing him, the divorce does not take effect unless it becomes impossible to inform him due to death. The actions of the husband's sister, namely sitting and conversing with a young man, are objectionable. She should be advised regarding this. Informing her brother is desirable if it is highly probable that doing so will lead to deterring her. The husband should combine firmness and leniency in reforming his sister.