Halakhah su Levitico 18:27

And the negative commandment of this prohibition was repeated in its stating, "and you shall not do from any of [these] abominations" (Leviticus 18:26), which includes all of these matters which are an abomination to God, may He be blessed. [This] means to say, that one who does them distances himself from the good and removes from himself the providence of God, blessed be He. And this is the understanding of the abominable to the Lord, may He be blessed, in every place, according to that which I have heard. And also that which is written at the end of the matter, "for all of these abominations did the people of the land that were before you do" (Leviticus 18:27), "and I was disgusted with them" (Leviticus 20:23). And the matter is to say that the trait is very disgusting. And every thing that is bad and very vile, Scripture describes as if God, may He be blessed, hates. And it is all according to the matter that we said; and similar to what they, may their memory be blessed, said in every place (Mekhilta d'Rabbi Yishmael 19:18:2), [it is] in order to break [to assuage] the ear to that which it can hear. And the language of Sifra, Achrei Mot, Section 8:8 is "'Like the deed of the land of Egypt and like the deed of the land of Canaan, etc.' (Leviticus 18:27) - perhaps they should not build or plant as they do? [Hence] we learn to say, 'and in their statutes you shall not walk.' I have only said those statutes which were instituted for them, and not their buildings. What did they do? A man would wed a man, and a woman, a woman; and a woman would wed two men."

He prohibited approaching one of these forbidden sexual relations - even without intercourse - such as [with] hugging and kissing, and similar such licentious acts. And that is His saying about its prohibition, "Each and every man - to any of his close kin - you shall not approach to uncover nakedness" (Leviticus 18:6) - as if to say, do not make any approach that leads to uncovering nakedness (sexual intercourse). And the language of the Sifra (Sifra, Acharei Mot, Chapter 13:15) is, "'You shall not approach to uncover nakedness' - I only know of nakedness. From where [do we know] not to approach? [Hence] we learn to say, 'To a woman, while in her menstrual impurity, you shall not approach to uncover her nakedness' (Leviticus 18:19). I only know about a menstruant, that she is [forbidden] with, do not approach and with, do not reveal. From where [do we know] about all of the sexual prohibitions, that they are [forbidden] with, do not approach and with, do not reveal? [Hence] we learn to say, 'you shall not approach to uncover.'" And there (Sifra, Acharei Mot, Chapter 13:21), they said, "'Their souls shall be cut off, those who do' (Leviticus 18:29) - what do we learn to say [from this]? Because it is stated, 'You shall not approach,' perhaps they would be liable for excision for approaching. [Hence] we learn to say, 'who do' - and not who approach." And the prohibition about these illusions was already repeated with His saying, "that you shall not do any of the abominable customs" (Leviticus 18:30). However His saying, "After the practice of the Land of Egypt in which you have lived, you shall not do; and the practice of the Land of Canaan, to which I am bringing you, you shall not do," is not only prohibiting the abominable customs - but indeed also prohibiting the actual abominations that He explained after this. And that which He brings two general negative statements about all of the prohibited sexual relations - is because when He prohibited not doing like the practice of the Land of Egypt and the practice of the Land of Canaan, this includes the lewdness, [but it also includes] the work of the land, the shepherding of animals and the settlement of the land as well. So He came back to explain that the actions that He prohibited [originally] were such and such sexual prohibitions that one should not uncover - and it is as He explained at the end of the [section], when He said, "For all of these abominations were done by the people of the land" (Leviticus 18:27). And the language of the [Sifra] (Sifra, Acharei Mot, Section 8:8) is, "Perhaps they should not build houses or plant vineyards like them. [Hence] we learn to say, 'and in their statutes (chukoteichem) you shall not walk' - only those statutes (chukim) which were instituted (chakukim) for them and for their forefathers." And there, they said, "What did they do? A man would wed a man, and a woman, a woman; and a woman would wed two men." Behold it has been made clear that these two negative commandments - being, "After the practice of the Land of Egypt [...] and the practice of the Land of Canaan [...] you shall not do" - are general commandments, being the prohibition of all of the sexual prohibitions (hence they not counted in the tally of the commandments). And afterwards, He repeated the prohibition of each sexual prohibition individually. And we ourselves have explained the regulations of these commandments in the seventh [chapter] of Sanhedrin in our great composition (Commentary on the Mishnah), and we explained that we are lashed for it. And it is from that which is fit for you to know that [in the case of] any woman for whom we would be liable excision, the [child] born from that intercourse is called a mamzer. And it is God, may He be exalted, who called him a mamzer (Deuteronomy 23:3). Whether that intercourse is volitional or whether it was inadvertent, the embryo is a mamzer - except specifically for the menstruant. One born from her is not a mamzer; however it is called the child of a menstruant. And this has already been explained in the fourth [chapter] of Yevamot. (See Parashat Achrei Mot; Mishneh Torah, Forbidden Intercourse.)