What is the ruling on the divorce oath, "By divorce, you will get up and do everything for the feast," which was uttered with the intention of compelling the wife to prepare the feast, especially given that the feast was postponed and the wife prepared it later?

You have divorced your wife by breaking your oath of divorce. You may take her back as long as her waiting period (iddah) has not ended, provided that this divorce does not complete the three divorces. This return (raj'ah) can be achieved by word or deed. You are obligated to perform two expiations for oaths (kaffarat yamin) because you broke your oath sworn by Allah. You must avoid oaths of divorce.