What is the ruling regarding someone who said to his wife, "You are unlawful to me," without intending divorce and without mentioning the word "mother" or "sister"?

Prohibiting one's wife depends on the husband's intention. If he did not intend divorce or ẓihār (a pre-Islamic form of divorce by likening one's wife to an unmarriageable relative), but rather intended to prevent his wife from something, or similar, then he is liable for an expiation for breaking an oath (kaffārat yamīn).