What is the ruling on the oath of divorce in the statement: "Divorce be upon me if you return except by the one who took you"? And what is the ruling on a wife riding alone with her sister's husband?

The brother is advised not to get angry, because anger makes a person lose self-control and act in ways he will regret.

As for the brother's swearing by divorce, "Upon me be divorce, no one will return you but the one who took you," scholars have differed regarding the occurrence of divorce: 1. The majority (the four schools of thought): They hold that divorce occurs if the condition is met, because it is a conditional divorce. 2. Sheikh al-Islam Ibn Taymiyyah: He does not consider divorce to occur; rather, it is an oath of prevention and intent, and it requires an expiation for an oath.

The preponderant opinion is that of the majority. The husband's intention should be considered: If his intention was: that the one who took her must return her, then divorce occurs according to the majority, or expiation is due according to Ibn Taymiyyah. If his intention was: that he himself would not return her, and there is no objection to anyone else returning her (the one who took her or someone else), then divorce does not occur and he does not break his oath, because intention specifies the general in an oath.

As for the questioner's action of returning the wife, her intention was good, to prevent unlawful seclusion with her sister's husband, but she fell into the same situation because she is not a mahram to the wife. Her sister's husband should have returned her, accompanied by one of the wife's mahrams, to negate unlawful seclusion, if this was the husband's intention. However, if his intention was that anyone other than him should return her, then one of her mahrams should return her.

It is recommended to refer the matter to the Sharia court or to knowledgeable scholars based on the specific circumstances.