תלמוד על שבת 128:15

What is the fence that the Torah made around its words? It says (Leviticus 18:19), “Do not come near woman during her period of impurity.” Perhaps [you would still think] one could hug her and kiss her and speak flirtatiously with her. So the verse tells you, “Do not come near.” Perhaps [you would still think] one could sleep next to her on the bed, as long as she was clothed. So the verse tells you, “Do not come near.” Perhaps [you would still think] she could wash her face and put makeup on her eyes. So the verse (Leviticus 15:33) tells you, “She is in her period of exile” – that is, all the days that she is in her period [of impurity], she will be in exile. Because of this they said: The spirit of the sages is pleased with anyone who makes herself unattractive during the days of her period [of impurity]. The spirit of the sages is displeased with anyone who makes herself attractive during the days of her period [of impurity].