What is the ruling on a husband saying, "By divorce, I will not go to lunch at my sister's house," and then he goes?

The majority of scholars hold that a conditional divorce takes effect upon the fulfillment of the condition, and this is the preponderant opinion. If a husband swears by divorce that he will not go to his wife's sister's house, and then he goes, the divorce takes effect according to the majority. The preponderant opinion is that this entails a single repudiation, not three. If this divorce has not been preceded by two repudiations, the husband can take his wife back before the completion of her iddah (waiting period). Sheikh al-Islam Ibn Taymiyyah and those who agreed with him are of the view that an expiation for an oath (kaffarat yamin) is required if the husband did not intend divorce.