What is the ruling regarding a man saying to his wife, "You are forbidden to me," and is expiation (kaffarah) required if they reconcile?

A man's statement to his wife, "You are forbidden to me," if he intends divorce by it, then divorce is binding upon him. If he intends ẓihār by it, then expiation is binding upon him, which is freeing a believing slave. If he is unable to do that, then fasting for two consecutive months. If he is unable to do that, then feeding sixty poor people. It is obligatory to abstain from intercourse and its preludes before performing the expiation. However, if he did not intend anything, then he owes an expiation for a broken oath (kaffārat yamīn): feeding ten poor people, or clothing them, or freeing a slave. If he is unable to do that, then he must fast for three days.