What is the expiation for a husband's oath if he swore by divorce upon his wife that she should not enter his brother's house, knowing that they have reconciled and the wife wishes to visit his sick brother's wife?

The majority of jurists hold that an oath of divorce cannot be revoked. Therefore, if the wife entered the house of the husband's brother, the divorce occurs, whether the husband intended divorce or merely a threat. This differs from the view of Ibn Taymiyyah, who holds that it is permissible to revoke it, and that if the intention was merely a threat, an expiation for breaking an oath is due. The effect of the oath ceases if the reason for it ceases. If a divorce occurs and it is not the third divorce, the husband may take his wife back as long as she is within her waiting period (iddah).