Does a husband's saying to his wife, "You are forbidden to me as my mother is forbidden to me," count as a divorce or a prohibition, and what is its legal ruling?

Polygyny is permissible, with its Shari'ah-compliant regulations, and the husband is not required to inform his first wife. The husband's desire for a second marriage does not permit the wife to insult him, harm him, or pray against him; rather, it is forbidden for her to do so.

Regarding the wife being declared unlawful like a mother (zihar): If the husband utters such a statement verbally, it is considered explicit zihar according to the Hanbalis. If the husband writes this in a message: - Some Hanbalis hold that it is zihar that takes effect simply by writing, even if not intended. - Others hold that it is an implicit statement (kinayah) that takes effect only with intention. - According to the Shafi'is, zihar by writing is like divorce by writing, and the correct view among them is that writing a divorce is an implicit statement (kinayah) that takes effect only with intention. Based on the premise that writing zihar is like writing divorce, and it is considered an implicit statement (kinayah) by most scholars, then if you intended zihar, the expiation for zihar becomes obligatory upon you before having intercourse with your wife. If you did not intend anything, then nothing is obligatory upon you.