Does an act of ẓihār occur if the husband imagined that he said to his wife, "O my sister," but the wife does not recall hearing this word, knowing that the husband was unaware that this word constitutes ẓihār, and what is the ruling on their living together for the past two years without fasting or expiation?

If a man calls his wife "my sister" or likens her to his sister, ẓihār (a pre-Islamic form of divorce by which a man likens his wife to an unmarriageable female relative) does not occur unless he intends it. In this case, the husband did not intend ẓihār by saying "my sister" because he does not know that this constitutes ẓihār, and the husband is unsure about what he said, and the wife confirms that she did not hear it. Therefore, they should not pay attention to these whispers and doubts.