Does a divorce occur in the aforementioned situations, especially after the husband swore, "Divorce be upon me if the person who is on the side of his wife's brother-in-law does not leave and take something," and then this person took it?

An oath of divorce is considered a conditional divorce by the majority of scholars, meaning the divorce takes effect upon the breach of the oath, and this is the fatwa (definition) we adopt. However, Ibn Taymiyyah holds that it does not constitute a divorce, and instead, an expiation for a broken oath is required. As for the first two cases, if the mufti (definition) in those cases was a known and learned scholar whom the husband followed, there is no need to ask again. In the second case, the divorce is considered to have occurred according to the view of the majority of scholars.