Why does the Torah add the (otherwise superfluous) word "Lo Siten Shechavt'cha Lezara"?
Ramban #1 and Moshav Zekenim #1: The Torah is giving a reason for the prohibition - inasmuch as, since it is impossible to ascertain from whose seed the woman gave birth 1 , and it will result in many abominations and harm to both men. 2
Ramban #2, R. Bachye #1 and Moshav Zekenim #2: To preclude lying with a married woman in order to hug and kiss, from Kareis 3 (without warning, and Chenek, where there is warning ? R. Bachye), even though they are forbidden. 4 5
Ramban #3 and R. Bachye #2 (both citing the Ibn Ezra) and Moshav Zekenim: Because intimacy is divided into three 6 objectives 7 - 1. To produce children (?le?Zara?); 8 2. To release some of the liquids that fill the body; 9 3. To give vent to one's animal instincts 10 - and the Torah is teaching us here that adultery with another man's wife is forbidden, even if it is to achieve the first objective.
Moshav Zekenim (citing R. Eliezer of Garmaiza): To teach us that the prohibition is not confined to someone who intended only for pleasure, but extends even to where a man's wife is sterile, and he is intimate with another man's wife in order to have children.
Yevamos 55b: To preclude where he is intimate with her with an Eiver Meis (a limp Eiver).
Ramban: Similarly, the Torah uses the same expression about Shifchah Charufah (19:20), lest a child result, and about a Sotah (Bamidbar 5:13), for this is the reason he warns her. It does not however do so when it discusses the punishment for Eshes Ish (20:18), because they are Chayav Kareis even for Ha'ara'ah (the beginning of intimacy, without Zera.)
Regarding marriage and Kibud Av, as well as complications regarding inheritance. See Ramban who elaborates further.
See Pasuk 29.
Ramban: And for the same reason the Torah inserts "le'Zera" by Sotah (Bamidbar, 5:13) and by Shifchah Charufah (Kedoshim,19:20)..
His body is punished in this world for touching (kissing and hugging) a married woman, and his Nefesh in Gehinom, for being intimate with her ? See R. Bachye - on page 512 - who elaborates.
The Moshav Zekenim does not mention the three objectives.
Which is a Mitzvah.
Which is permitted.
Why does the Torah use the term "Le'tam'ah-bah" in connection with Eishes Ish and Beheimah (in Pasuk 23)?
Oznayim la'Torah: Because someone who commits adultery with another man's wife can be compared to an animal, which share a spouse with one another. 1 And one can add that the Torah mentions "Tum'ah by Eishes Ish, to teach us that she becomes Tamei and remains permanently forbidden to him. 2
Oznayim la'Torah: As the Gemara states in Sotah, 14a - in connection with a Sotah - 'Just as she behaved like an animal, so too, does her Korban consist of animal food - barley'.
As the Gemara states there - Daf 28a 'Just as she is forbidden to her husband, so too, is she forbidden to the adulterer
