Why does the Torah juxtapose Achoso on the pne side, and NIdah on the other? (What do they hsve in common)?
Ba'al ha'Turim: Because all three live with him in the same house (and are therefore always available).
Why does the Torah write "ve'Ish asher Yikach ... ", in spite of the fact that "Yikach"implies Kidushin and Kidushin with a sister is not effective?
Ramban and Moshav Zekenim: Because a sister is brought up in the same house as her brother, and if he develops a desire for her, it is easy to take her without having to go to her as one does with a Zonah. 1
Ramban and Moshav Zekenim: In fact, this explains why the Torah employs the expression "Ki Yikach" by all the cases of incest where the pair are living together - See 20:14, 20:1, 20:19 & 23:1.
Why does the Torah write here "ve'Ra'ah es Ervasah"?
Ramban and Moshav Zekenim: The Torah refers to the act of intimacy discreetly, using many different expressions, usually 'Giluy Ervah', 1 but sometimes 'Bi'ah', 2 often with a expression of 'Shechivah' and on some occasions even as 'Yedi'ah'. 3 Here, it decribes it as 'Re'iyah', and not Giluy, since they normally sleep together, and he does not even need to remove her garment (or blanket).
Sanhedrin, 40b: To teach us that Beis-Din may only punish a sinner after he has been warned by witnessses 4 - to ensure that he sees what he has done wrong before he can receive Malkos. 5
Oznayim la'Torah: The Torah refers to Re'iyah (looking at a location of Ervah) 6 here and to Giluy (revealing Ervah) in other places. 7 It also forbids Yichud (seclusion) - all of which we do not find by any other Aveirah -due to the attraction of the actual sin itself, which is more powerful that of any other sin. 8 That is why the Torah forbids the above, to prevent finding oneself in a situation where it is all but impossible to avoid sinning.
Ramban and Moshav Zekenim: As this is what is commonly done (See for example, Nachum, 3:5).
Ramban: See for example, Devarim 22:13.
Ramban: See for example Bereishis, 4:1 and Vayeishev Bereishis,38:26. See also Ba'al ha'Turim.
Torah Temimah: To confine Malkos to where witnesses warned the sinner of the consequences of the act that he is about to perform. See Torah Temimah, note 41.
Sanhedrin (Ibid.): 'Im Eino Inyan' - Seeing as this D'rashah is not applicable to Kareis, and Chiyuv Kareis is subject to Malkos See Torah Temimah, note 42..
See also Ba'al ha'Turim.
Oznayim la'Torah: See for example, Pasuk 11 & 18, 20 & 21.
See Oznayim la'Torah who elaborates at length and explains how originally, the same applied to the sin of Avodah Zarah and why this is no longer the case.
Why does the Torah write "ve'Hi Sir'eh" (future) and not ve'Hi Ra'ah es Ervaso" (in the past - like it writes "Vera'ah es Ervasah") by the man?
Oznayim la'Torah (citing Kesuvos, 64b): Because the Yeitzer ha'Ra of a woman is not as powerful as that of a man, 1 in which case she only looks at him after he has incited her by looking at her. 2
Oznayim la'Torah (Ibid.): 'In a 'Shuk shel Zonos (a brothel), who hires whom?'
Oznayim la'Torah (citing Tosfos, Bava Kama, 41a DH 'ke'Ma'an'): This does not absolve her from the death-penalty however, as Chazal say it does there where she is initially raped and then continues willingly - 'Yitzrah Alb'shah' (Kesuvos, 51b).
What is the meaning of "Chesed Hu"?
Rashi #1, Rashbam, Ramban #1 and Targum Onkelos: It means 'a disgrace'. 1
Rashi #2 and Targum Yonasan: To teach us that Kayin (and Hevel - Yerushalmi Yevamos, 1:1) was allowed to marry his sister 2 because Chesed on the part of Hashem to enable the world to become inhabited. 3
Ramban #2 and Moshav Zekenim (both citing the Yerushalmi, Yevamos, 11:1): It means literally 'lovingkindness', as it refers (not to what was done, but) to what is expected of siblings - to behave with lovingkindness towards one another. He should rather have married her to a man, and not blemished her!
Rashbam: as in Mishlei, 25:10 & 14:34. Ramban: See also Targum Onkelos, Bereishis, 34:14, and Targum Yonasan, Shmu'el 1, 11:2. R. Chananel: Mishlei, 14:34 (Refer to 20:17:3:3*). Rashi adds that it is actually an Arama'ic word.
Targum Yonasan: Before the Torah which prohibits it was given.
Rashi: As the Pasuk writes in Tehilim, 89:3 "Olam Chesed Yibaneh".
Instead of performing a Chesed and permitting Kayin to marry his sister - something that the Torah ultimately forbids, why did Hashem not create two couples, whose children would then marry one another?
Oznayim la'Torah #1 (citing Sanhedrin, 38a): To prevent people from claiming that two gods created the world each of whom created one couple, or in order to prevent their descendents a. from squabling over whose family is more important or b. from stealing each other's land (on the petext that it had previously belonged to their ancestors and the other family had stolen it).
Oznayim la'Torah #2: Given the unlikelihood of two people living together encountering differences of opinion, 1 Hashem created woman directly from man, thereby creating a natural bond that would bind them together, enabling them to spending fifty or sixty years together peacefull without constantly quarreling. 2
Why does the Torah mention Kareis by Achoso, seeing as she is included in the Kareis that incorporates all the Arayos (in 18:29)?
Kerisos, 2b: To teach us that one is Chayav even if she is both one's paternal and maternal sister. 1
Ramban and Moshav Zekenim (both on Pasuk 9): It adds to this "le'Einei B'nei Amam" - they will die young, so that everyone will understand that they were struck by Hashem's Hand.
Moshav Zekenim (citing Makos 14a): This teaches us that someone who transgresses several Arayos in one He'elam, is liable a Chatas for each one.
Makos 14a(According to R. Yitzchak): To teach us that one is Chayav Kareis for his sister, and is not subject to Malkos - and the same applies to all Chayvei Kerisos.
Moshav Zekenim: In order not to learn from Nidah thr Chiyuv Ha'ara'ah - One is liable for a sister only for full intimacy. 2
See Torah Temimah, who discusses how this is possible. Refer also o 20:17:152:1.
This would answer the Ritva's question (Kidushin 77b) about a Kohen who had Bi'ah with his sister (she does not become a Zonah until full Bi'ah), but I cannot resolve it with Yevamos 54a which says that one is liable for all Arayos for Ha'ara'ah. (PF)
Why does the Pasuk insert the words "le'Einei B'nei Amam"?
Refer to 20:17:4:2.
Ramban and Moshav Zekenim (both in Pasuk 9): To point ut that they may have sinned in secret, but Hashem will punish them before the eyes of all the people - who will see how they died young. 1
Ramban and Moshav Zekenim: The Torah writes it here, about a sin done covertly (people do not see him go to the Ervah's house), but it extends to all the Chayvei Kerisos.
What are the implications of "Avono Yisa'?
Ramban and Moshav Zekenim (both in Pasuk 9): From the moment they sin, they will begin to fail in all their undertakings and they will be stricken with illnesses. 1
Ramban: See Shabbos, 33a.
Why does the Pasuk begin in the plural and end in the singular?
Ramban #1 (citing the Ibn Ezra): To teach us that if the man rapes his sister against her will, 1 then only he is subject to Kareis, and not she. 2
Ramban #2: "Venichr'su" indicates that "Avono Yisa" refers to each one. 3
Oznayim la'Torah: Even if she acquieces in the middle ('Yeitzer Alb'shah') - as the Gemara explains in Kesuvos, 51a, seeing as initially she was an Oneis.
Ramban (DH ve'Hi Sir'eh): Here the Torah said "ve'Hi Sir'eh es Ervaso", since they sleep together and perhaps she did not consent. Other Arayos, she realizes that he is coming close; if she objects, she should scream! (Likewise, it says about Nidah (Pasuk 18) "ve'Hi Gilsah?", for perhaps she did not consent. - PF)
Ramban: As in Pasuk 19, where it is more evident.
Why does the Torah not discuss the punishment for granddaughters?
Ibn Ezra #1 and Moshav Zekenim #1:Because it relies on the Oral Torah.
Ibn Ezra #2 and Moshav Zekenim #2: Because it is not common, since when his granddaughters mature, he is old and his lust has waned. Likewise, it does not mention grandmothers, since they are old. 1
The Torah does not forbid one's grandmother. It did not explicitly mention the punishment for his wife's grandmothers and granddaughters. (PF)
Why does the Torah add the (othersie superfluous) phrase "Ervas Achoso Gilah"?
Makos 5b: Because, having already discussed a half-sister, the current Pasuk is discussing a full sister - to teach us the principle 'Ein Onshin Min ha'Din' ('We cannot punish 1 based on a Kal va'Chomer).
