What is the ruling on a man who says to his wife, "You are forbidden to me"?

Question : A man said to his wife, "You are forbidden to me if you do such and such," and she did it. So this man fasted for two months, but he had intercourse with his wife during these two months. What is required of him, Honorable Shaykh?

Answer : First, this man issued a ruling for himself. Because he claimed that saying "You are forbidden to me if you do such and such" falls under the category of zihar.
And he began fasting the two months, but he had intercourse before they were completed. We say that a man saying to his wife, "You are forbidden to me if you do such and such," is not zihar. Rather, its ruling is the ruling of an oath. If she did it, he owes the expiation for an oath; if she did not do it, he owes nothing. The evidence that prohibition is an oath is the saying of Allah, Blessed and Exalted is He: So He named it, and Allah made the prohibition an oath. Therefore, if a man says to his wife, "You are forbidden to me," or "If you do such and such, you are forbidden to me," this is not zihar. Rather, it is what?
It is an oath for which he expiates with the expiation for an oath, and the ruling of this matter is lifted. So we tell the brother: if you consulted a scholar you trust and he told you that this is zihar, and you had intercourse with her before you completed fasting the two months, then you have sinned. But if you issued a ruling for yourself and you are not one of the people of fatwa, then you erred in the original matter of obligating yourself to the two months. Yes.