Has the husband broken his oath by swearing to divorce his wife if she speaks to her neighbor, if she then spoke to her out of forgetfulness? Is expiation (kaffarah) required of him after having intercourse with his wife? Is it permissible to authorize his brother, who resides in Egypt, to pay the expiation while he (the husband) resides in Europe?

There is a difference of opinion among jurists as to whether a divorce occurs if the wife does the sworn-upon act out of forgetfulness. Some scholars have chosen the opinion that it does not occur, based on what Al-Nawawi said: "If the sworn-upon statement or action occurs under duress, or forgetfulness, or ignorance, whether the oath was by Allah Almighty or by divorce, does one break the oath? There are two opinions, the most apparent of which is that one does not break the oath." Based on this, the divorce did not occur when your wife spoke to your neighbor out of forgetfulness, and there is no expiation upon you. One should be wary of hastily uttering divorce, and be keen on resolving problems with neighbors, for they have great rights.