Halakhah su Levitico 18:20

To not reveal the nakedness of a man's wife: To not have intercourse with a man's wife, as it is stated (Exodus 20:13), "You shall not commit adultery." And the explanation comes that the undifferentiated expression, "adultery," indicates with a man's wife, as they, may their memory be blessed, said (Rashi on Exodus 20:13), "Adultery is only with a man's wife." And this negative commandment is repeated in the Order of Achrei Mot, as there it is written explicitly (Leviticus 18:20), "And to your neighbor's wife, etc."

He prohibited us from sexual intercourse with a married woman. And that is His, may He be exalted, saying, "And to the wife of your kinsman do not give your lying for seed to become unclean to her" (Leviticus 18:20). And there are distinctions about the punishment for one that transgresses this negative commandment: And that is that [in a case of] a married woman that was [just] a betrothed maiden, both of them are liable for stoning, as Scripture explained. But if she was fully married: If she was an Israelite and fully married, they are both liable for strangulation. However if she was the daughter of a priest and fully married, her law is [the punishment of] burning, and he - meaning the one who had intercourse [with her] - is [punished] with strangulation. And that is when the testimony is ratified. But if he was inadvertent, he must sacrifice a fixed sin-offering. And the prohibition about this was already repeated with His saying, "you shall not commit adultery" (Exodus 20:13) - meaning to say with this, not to have sexual intercourse with a married woman. And the language of the Mekhilta (Mekhilta d'Rabbi Yishmael 20:13:2) is, "'You shall not commit adultery' - why is it stated? Since it states, 'The adulterer and the adulteress shall be put to death' (Leviticus 20:10), we understand the punishment. From where [do we know] the prohibition? [Hence] we learn to say, 'You shall not commit adultery.' It is the same for the man and for the woman." And this is not like, "And to the wife of your kinsman" - for that is a prohibition that does not include an adulterer and an adulteress, but is a prohibition for the adulterer alone. And likewise with the other sexual prohibitions. It was impossible that they not derive [the prohibition] also for the woman, from His saying, "you (plural) shall not approach to uncover [their] nakedness" (Leviticus 18:6): "Behold there are two (it is plural)! To prohibit a man with a woman and a woman with a man" (Sifra, Acharei Mot, Chapter 13:1). And in the Gemara, Sanhedrin (Sanhedrin 51b), they said, "All [adulterers] were included in, 'The adulterer and the adulteress.' Scripture singled out the daughter of a priest for burning, and the betrothed maiden for stoning." And the explanation of this matter has already been discussed in the introduction to this essay.