Is likening one's wife to a woman prohibited temporarily a form of Zihar (declarative divorce)?
General Chapter
Al-Mughni
Book of Zihar
Primary text
There are two narrations from Ahmad concerning a man likening his wife to a woman whom he is temporarily forbidden to marry, such as his wife's sister, his paternal aunt (if she is not permanently forbidden), or a non-related woman. One narration holds that it constitutes Zihar, which is the choice of Al-Khiraqi and the position of the companions of Malik. The evidence for this view is that he likened her to a woman who is forbidden to him, thus resembling the case where he likens her to the mother. Furthermore, the simple statement "You are forbidden to me" constitutes Zihar if he intends Zihar, and likening her to a forbidden woman implies prohibition, making it Zihar.
Supporting text
The second narration states it is not Zihar, which is the position of Al-Shafi'i. The reasoning is that she is not permanently forbidden, so likening her does not constitute Zihar, similar to a menstruating woman or a woman in the state of Ihram (for pilgrimage) from among his permissible wives. This is contrasted by noting that while the menstruating woman can be enjoyed in ways other than intercourse, and the woman in Ihram can be looked at or touched without desire, there is no prescribed penalty for intercourse with either of those two, unlike the case in question.