Levitico 18:19 Cabala: Zohar, Reshit Chokhmah & Idra Zuta

Come and behold, As I have said, for Bilaam used to defile himself first to draw upon him the unholy spirit. Similarly, it behooves man to stay away from a woman during menstruation, because she is attached to the spirit of defilement. If she practices sorcery at that time, she will be more successful that at other times. Whatever she touches is therefore defiled, and all the more so whomever approaches her. Happy are the children of Yisrael, for the Holy One, blessed be He, gave them Torah, and told them, "Also you shall not approach to a woman in the impurity of her menstrual flow, to uncover her nakedness... I am Hashem" (Vayikra 18:19-21).

357. How did Yisrael merit to welcome the Shechinah? It is through guarding against the impurity of menstruation. And about this is written: “Also you shall not approach a woman in the impurity of her menstrual flow, to uncover her nakedness” (Vayikra 18:19). HE ASKS: “To uncover her nakedness” – of whom? HE ANSWERS: Of the Congregation of Yisrael, MEANING NOT TO BLEMISH HER. And in this way, other things that the Congregation of Yisrael is bound to join and connect to Her. And we have already explained this matter.

Regarding conversation with a Niddah woman, it is explained in Midrash Rabbah (Bamidbar Rabbah 10:8): Why did the Torah prohibit grape extract and all that comes from grapes if one cannot get drunk from them? From here we learn that one must distance himself from anything repulsive and anything similar, and we also learn that the Torah made a safeguard/fence for its words. We also learned (Pirkei Avot chapter 1) “Be cautious in judgement, establish many pupils, and make a safety fence around the Torah.” How? Make a safety fence for your words just like the Torah did for its words, as it says “you may not come close to a woman during her Niddah period to reveal her nakedness” (Leviticus 18:19); I would think it would be permitted to hug and kiss her and speak to her about mundane things; we thus learn “you may not come close”. I would think it would be permitted to sleep next to her with her clothes on; we thus learn “you may not come close”. I would think it would be permitted if she washes her face and color her eyes blue and I would take a cup to drink from her hands; we thus learn, “and of her that is sick with her impurity” (Leviticus 15:33), all the days that she is impure she is “banned” (Nidui) from her husband. From here they say that one who makes herself look unattractive during her period pleases the spirit of the Sages, and one who puts ornaments and make-up during her period displeases the spirit of the Sages.