Sanhedrin 53
בִּשְׁלָמָא לְרַבִּי יוֹנָתָן, כִּדְקָא מְפָרֵשׁ רַבִּי טַעְמָא. אֶלָּא לְרַבִּי יֹאשִׁיָּה, מִמַּאי דְּאִיכָּא חֶנֶק בָּעוֹלָם? אֵימָא סַיִיף!
Granted, according to Rabbi Yonatan it is clear the punishment for adultery is strangulation, in the manner that Rabbi Yehuda HaNasi explains the reason for his opinion. But according to Rabbi Yoshiya, from where is it derived that there is a punishment of execution by strangulation in the world, i.e., in halakha, at all? Since this type of capital punishment is not mentioned in the Torah explicitly, say that decapitation by the sword is the least severe type, as it is mentioned in the Torah.
אָמַר רָבָא: אַרְבַּע מִיתוֹת גְּמָרָא גְּמִירִי לְהוּ.
Rava said: The four types of the death penalty are learned as a tradition. There is no question as to the types of capital punishment that exist in halakha. Rather, the question is which type of execution is meted out as punishment for which sins.
מַאי ״לֹא מִפְּנֵי שֶׁהִיא קַלָּה״? קָמִיפַּלְגִי בִּפְלוּגְתָּא דְּרַבִּי שִׁמְעוֹן וְרַבָּנַן.
The Gemara asks: What is meant by Rabbi Yonatan’s statement: It is not because strangulation is the most lenient type of capital punishment? The Gemara answers: At the root of the matter, Rabbi Yonatan and Rabbi Yoshiya disagree with regard to the issue that is the subject of the dispute between Rabbi Shimon and the Rabbis, i.e., whether strangulation or decapitation is the least severe type of execution. Consequently, Rabbi Yonatan does not employ the reasoning that strangulation is the least severe.
אֲמַר לֵיהּ רַבִּי זֵירָא לְאַבָּיֵי: שְׁאָר הַנִּסְקָלִין דְּלָא כְּתִיב בְּהוּ סְקִילָה, דְּגָמְרִי מֵאוֹב וְיִדְּעוֹנִי, בְּמַאי גָּמְרִי? בְּ״מוֹת יוּמָתוּ״ גָּמְרִי, אוֹ בִּ״דְמֵיהֶם בָּם״ גָּמְרִי?
§ Rabbi Zeira said to Abaye: With regard to the rest of those transgressors, other than necromancers and sorcerers, who are stoned to death, with regard to whom stoning is not explicitly written in the Torah because their punishment is derived via a verbal analogy from that of a necromancer and a sorcerer, about which the verse states: “They shall be put to death, they shall stone them with stones, their blood shall be upon them” (Leviticus 20:27); through what verbal analogy is their punishment derived? Is it derived from the phrase “they shall be put to death,” or is it derived from the phrase “their blood shall be upon them”?
אֲמַר לֵיהּ: בִּ״דְמֵיהֶם״ ״דְּמֵיהֶם בָּם״ גָּמְרִי, דְּאִי בְּ״מוֹת יוּמָתוּ״ גָּמְרִי, ״דְּמֵיהֶם״ ״דְּמֵיהֶם״ לְמָה לִי?
Abaye said to him: It is derived from a verbal analogy between “their blood” and “their blood shall be upon them.” As, if it is derived from “they shall be put to death,” why do I need the verbal analogy between “their blood” and “their blood”? Why does this term need to be written with regard to the various halakhot?
אֶלָּא מַאי, בִּ״דְמֵיהֶם״ ״דְּמֵיהֶם״ גָּמְרִי? ״מוֹת יוּמָתוּ״ לְמָה לִי?
The Gemara asks: Rather, what is more reasonable? If it is derived from the verbal analogy between “their blood” and “their blood,” the same problem arises: Why do I need the phrase “they shall be put to death”?
כִּדְתַנְיָא: ״מוֹת יוּמַת הַמַּכֶּה רֹצֵחַ הוּא״ – אֵין לִי אֶלָּא בְּמִיתָה הַכְּתוּבָה בּוֹ. מִנַּיִין שֶׁאִם אִי אַתָּה יָכוֹל לַהֲמִיתוֹ בְּמִיתָה הַכְּתוּבָה בּוֹ, שֶׁאַתָּה מְמִיתוֹ בְּכׇל מִיתָה שֶׁאַתָּה יָכוֹל לַהֲמִיתוֹ? תַּלְמוּד לוֹמַר: ״מוֹת יוּמַת הַמַּכֶּה״ – מִכׇּל מָקוֹם.
The Gemara answers: This expression is necessary, as another halakha is derived from it. As it is taught in a baraita: The verse with regard to a murderer states: “He that smote him shall be put to death, for he is a murderer” (Numbers 35:21). I have derived only that the murderer is put to death with the mode of execution written concerning him, i.e., by decapitation. From where do I derive that if you cannot put him to death with the mode of execution written concerning him, e.g., if the condemned man will escape if one does not kill him, that you put him to death with any mode of execution with which you can put him to death? The verse states: “He that smote him shall be put to death [mot yumat],” the doubled verb teaching that he is put to death in any case, i.e., by any mode of execution.
אֲמַר לֵיהּ רַב אַחָא מִדִּפְתִּי לְרָבִינָא: וְאִי בְּ״מוֹת יוּמָתוּ״ גָּמְרִי, מַאי קָא קַשְׁיָא לֵיהּ?
This exchange between Rabbi Zeira and Abaye was subsequently discussed by later amora’im. Rav Aḥa of Difti said to Ravina: And if the halakha that there are transgressors other than necromancers and sorcerers who are punished by stoning is derived from “they shall be put to death,” what is difficult according to Rabbi Zeira? It appears from Rabbi Zeira’s question that he was troubled by the possibility that this halakha is derived from the phrase “they shall be put to death.”
אִילֵּימָא אֵשֶׁת אִישׁ קָא קַשְׁיָא לֵיהּ, לְמֵיתֵי וּלְמִיגְמַר ״מוֹת יוּמַת״ מֵאוֹב וְיִדְּעוֹנִי: מָה לְהַלָּן בִּסְקִילָה, אַף כָּאן בִּסְקִילָה?
If we say that the case of adultery of a married woman would pose a difficulty according to Rabbi Zeira, as it is stated: “The adulterer and the adulteress shall be put to death” (Leviticus 20:10), and therefore perhaps we should derive and learn from the phrase “they shall be put to death” stated with regard to a necromancer and a sorcerer that just as there, with regard to a necromancer and a sorcerer, they are executed by stoning, so too here, with regard to adultery, the transgressors should be executed by stoning, this does not pose a difficulty.
מִדְּאָמַר רַחֲמָנָא אֲרוּסָה בִּסְקִילָה, מִכְּלָל דִּנְשׂוּאָה לָאו בִּסְקִילָה.
Rav Aḥa of Difti explains why it does not pose a difficulty: From the fact that the Merciful One states that a betrothed woman who committed adultery is executed by stoning, by inference we learn that a married woman who committed adultery is not executed by stoning, but rather she is executed by a less severe type of execution. Therefore, it could not have been derived from the case of a necromancer and a sorcerer that the punishment for the adultery of a married woman is execution by stoning.
וְאֶלָּא, מַכֵּה אָבִיו וְאִמּוֹ קָא קַשְׁיָא לֵיהּ, לְמֵיתֵי וּלְמִיגְמַר מֵאוֹב וְיִדְּעוֹנִי?
And if it is rather the case of one who wounds his father or his mother that poses a difficulty according to Rabbi Zeira, as it is stated: “And he who smites his father or his mother shall be put to death” (Exodus 21:15), and therefore perhaps we should derive and learn from the punishment of a necromancer and a sorcerer that one who wounds his father or his mother should be executed by stoning, this too does not pose a difficulty.
עַד דְּגָמְרִי מֵאוֹב וְיִדְּעוֹנִי, לִיגְמְרוּ מֵאֵשֶׁת אִישׁ, דְּאִי אַתָּה רַשַּׁאי לְמוֹשְׁכָהּ לְהַחְמִיר עָלֶיהָ, אֶלָּא לְהָקֵל עָלֶיהָ.
Rav Aḥa of Difti explains why it does not pose a difficulty: Rather than deriving the punishment of one who wounds his father or his mother from a necromancer and a sorcerer, let us derive it from adultery with a married woman, as everywhere that the death penalty is stated in the Torah without specification you may not take it to be more stringent with regard to it, i.e., to mean that the sinner should be sentenced to a severe type of execution; rather, you must take it to be more lenient with regard to it, i.e., that a lenient type of execution should be applied. Since in both the case of adultery and the case of one who wounds his parent the type of execution is evidently not stoning, why was Rabbi Zeira troubled by the possibility that the source for execution by stoning in cases other than a necromancer and a sorcerer is derived from the phrase: “They shall be put to death”?
אֲמַר לֵיהּ: שְׁאָר הַנִּסְקָלִין גּוּפַיְיהוּ קָא קַשְׁיָא לֵיהּ, דְּאִי בְּ״מוֹת יוּמָת״ גָּמְרִי, עַד דְּגָמְרִי מֵאוֹב וְיִדְּעוֹנִי, לִיגְמְרוּ מֵאֵשֶׁת אִישׁ!
Ravina said to Rav Aḥa of Difti: It is the halakha concerning the rest of those who are stoned, themselves, which poses a difficulty according to Rabbi Zeira. This is because if their punishment is derived from the phrase “they shall be put to death,” then rather than deriving from the case of a necromancer and a sorcerer that these transgressors are executed by the severe method of stoning, let us derive from the case of one who commits adultery with a married woman, with regard to whom “they shall be put to death” is also stated, that they should be executed by strangulation, the less severe method. He therefore verified that it is derived from the phrase “their blood shall be upon them,” that they are executed by stoning.
מַתְנִי׳ אֵלּוּ הֵן הַנִּסְקָלִין: הַבָּא עַל הָאֵם, וְעַל אֵשֶׁת הָאָב, וְעַל הַכַּלָּה, וְעַל הַזְּכוּר, וְעַל הַבְּהֵמָה, וְהָאִשָּׁה הַמְּבִיאָה אֶת הַבְּהֵמָה. וְהַמְגַדֵּף, וְהָעוֹבֵד עֲבוֹדָה זָרָה, וְהַנּוֹתֵן מִזַּרְעוֹ לַמּוֹלֶךְ, וּבַעַל אוֹב וְיִדְּעוֹנִי, וְהַמְחַלֵּל אֶת הַשַּׁבָּת, וְהַמְקַלֵּל אָבִיו וְאִמּוֹ, וְהַבָּא עַל נַעֲרָה הַמְאוֹרָסָה, וְהַמֵּסִית, וְהַמֵּדִיחַ, וְהַמְכַשֵּׁף, וּבֵן סוֹרֵר וּמוֹרֶה.
MISHNA: These transgressors are those who are stoned to death: One who engages in intercourse with his mother; or with his father’s wife, even if she is not his mother; or with his daughter-in-law; or with a male; or with an animal; and a woman who engages in intercourse with an animal. And one who blasphemes, and one who engages in idol worship. And one who gives of his offspring to Molekh, and a necromancer, and a sorcerer. And one who desecrates Shabbat, and one who curses his father or his mother, and one who engages in intercourse with a betrothed young woman, and an inciter who incites individuals to idol worship, and a subverter who incites an entire city to idol worship, and a warlock, and a stubborn and rebellious son.
הַבָּא עַל הָאֵם, חַיָּיב עָלֶיהָ מִשּׁוּם אֵם וּמִשּׁוּם אֵשֶׁת אָב. רַבִּי יְהוּדָה אוֹמֵר: אֵינוֹ חַיָּיב אֶלָּא מִשּׁוּם הָאֵם בִּלְבַד.
The mishna elaborates: One who unwittingly engages in intercourse with his mother who is also his father’s wife is liable to bring two sin-offerings for his intercourse with her: One due to the prohibition against engaging in intercourse with one’s mother and one due to the prohibition against engaging in intercourse with one’s father’s wife. Rabbi Yehuda says: He is liable to bring only one sin-offering, due to the prohibition against engaging in intercourse with one’s mother.
הַבָּא עַל אֵשֶׁת אָב, חַיָּיב מִשּׁוּם אֵשֶׁת אָב וּמִשּׁוּם אֵשֶׁת אִישׁ, בֵּין בְּחַיֵּי אָבִיו בֵּין לְאַחַר מִיתַת אָבִיו, בֵּין מִן הָאֵירוּסִין בֵּין מִן הַנִּישּׂוּאִין.
One who unwittingly engages in intercourse with his father’s wife while his father is married to her is liable to bring two sin-offerings: One due to the prohibition against engaging in intercourse with one’s father’s wife and one due to the prohibition against engaging in intercourse with a married woman. He is liable due to the former prohibition both during his father’s lifetime and after his father’s death, and whether the relationship between the woman and his father is one of betrothal or one of marriage.
הַבָּא עַל כַּלָּתוֹ, חַיָּיב עָלֶיהָ מִשּׁוּם כַּלָּתוֹ וּמִשּׁוּם אֵשֶׁת אִישׁ, בֵּין בְּחַיֵּי בְנוֹ בֵּין לְאַחַר מִיתַת בְּנוֹ, בֵּין מִן הָאֵירוּסִין בֵּין מִן הַנִּישּׂוּאִין.
Likewise, one who unwittingly engages in intercourse with his daughter-in-law during his son’s lifetime is liable to bring two sin-offerings for his intercourse with her: One due to the prohibition against engaging in intercourse with one’s daughter-in-law, and one due to the prohibition against engaging in intercourse with a married woman. The former liability applies both during his son’s lifetime and after his son’s death, and whether the relationship between the woman and his son is one of betrothal or one of marriage.
גְּמָ׳ תַּנְיָא: רַבִּי יְהוּדָה אוֹמֵר, אִם לֹא הָיְתָה אִמּוֹ רְאוּיָה לְאָבִיו, אֵינוֹ חַיָּיב אֶלָּא מִשּׁוּם הָאֵם בִּלְבַד.
GEMARA: With regard to one who engages in intercourse with his mother, it is taught in a baraita that Rabbi Yehuda says: If his mother was not suitable for his father, as their marriage was forbidden, he is liable only due to the prohibition against engaging in intercourse with one’s mother, and not due to the prohibition against engaging in intercourse with one’s father’s wife.
מַאי ״אֵינָהּ רְאוּיָה לוֹ״? אִילֵּימָא חַיָּיבֵי כָרֵיתוֹת וְחַיָּיבֵי מִיתוֹת בֵּית דִּין, מִכְּלָל דְּרַבָּנַן סָבְרִי אַף עַל גַּב דְּאֵינָהּ רְאוּיָה לוֹ? הָא לֵית לֵיהּ קִידּוּשִׁין בְּגַוַּוהּ!
This is clarified: What does it mean that she is not suitable for him? If we say that the mother and father were liable to receive the punishment of excision from the World-to-Come [karet], or liable to receive a court-imposed death penalty for their intercourse, in which case their marriage did not take effect and therefore Rabbi Yehuda holds that in this case there is no prohibition against engaging in intercourse with one’s father’s wife, this poses a difficulty. As accordingly, by inference, in may be understood that the Rabbis hold that there is such a prohibition even if she is not suitable for him. Doesn’t everyone agree that in such a case the father has no capability of betrothal with regard to her? Even if they cohabit, she is not considered his wife.
אֶלָּא: חַיָּיבֵי לָאוִין, וְרַבִּי יְהוּדָה סָבַר לַהּ כְּרַבִּי עֲקִיבָא, דְּאָמַר: אֵין קִידּוּשִׁין תּוֹפְסִין בְּחַיָּיבֵי לָאוִין.
Rather, it is clear that Rabbi Yehuda is referring to a case where the father and mother are liable for violating a prohibition for their intercourse, but they are not liable to receive karet or capital punishment. And Rabbi Yehuda in this matter holds in accordance with the opinion of Rabbi Akiva, who says that betrothal does not take effect with those women with regard to whom one is liable for violating a prohibition if one engages in intercourse with them. The Rabbis disagree with this; in their opinion, betrothal does take effect in such cases, although a prohibition is involved. Therefore, the mother is considered the father’s wife, and the son is liable for engaging in intercourse with his father’s wife as well as for engaging in intercourse with his mother.
מֵתִיב רַב אוֹשַׁעְיָא: אִיסּוּר מִצְוָה וְאִיסּוּר קְדוּשָּׁה – חוֹלְצוֹת וְלֹא מִתְיַיבְּמוֹת.
Rav Oshaya raises an objection to this explanation, as it is stated in a mishna in tractate Yevamot (20a): If a yevama is forbidden to her yavam by a prohibition resulting from a mitzva or by a prohibition stemming from sanctity, then since in these cases the levirate bond is not fundamentally nullified, she performs ḥalitza in order to become free of the levirate bond, and due to the prohibition she does not enter into levirate marriage.
אִיסּוּר מִצְוָה – שְׁנִיּוֹת מִדִּבְרֵי סוֹפְרִים. וְאַמַּאי קָרוּ לְהוּ אִיסּוּר מִצְוָה? שֶׁמִּצְוָה לִשְׁמוֹעַ דִּבְרֵי חֲכָמִים.
The mishna explains: A prohibition resulting from a mitzva is referring to secondary forbidden relatives, e.g., one’s son’s daughter-in-law, who are forbidden by rabbinic law. The Sages instituted this prohibition in order to distance people from incest. The Gemara explains: And why do the Sages call it a prohibition resulting from a mitzva? Because it is a mitzva to listen to the words of the Sages.
אִיסּוּר קְדוּשָּׁה – אַלְמָנָה לְכֹהֵן גָּדוֹל, גְּרוּשָׁה וַחֲלוּצָה לְכֹהֵן הֶדְיוֹט. וְאַמַּאי קָרוּ לְהוּ אִיסּוּר קְדוּשָּׁה? דִּכְתִיב: ״קְדֹשִׁים יִהְיוּ לֵאלֹהֵיהֶם״.
The mishna continues: A prohibition stemming from sanctity is referring to the marriage of a widow to a High Priest, or to the marriage of a divorcée or of a woman who has performed ḥalitza [ḥalutza], to an ordinary priest. The Gemara explains: And why do the Sages call it a prohibition stemming from sanctity? As it is written with regard to the priests: “They shall be sanctified to their God” (Leviticus 21:6).
וְתַנְיָא עֲלַהּ: רַבִּי יְהוּדָה מַחְלִיף.
And it is taught in a baraita with regard to this mishna: Rabbi Yehuda switches the terms; he refers to the marriage of a divorcée or of a ḥalutza to a priest as a prohibition resulting from a mitzva, and to the marriage of secondary relatives as a prohibition stemming from sanctity.
חַלּוֹפֵי הוּא דְּמַחְלֵיף, הָא חֲלִיצָה בָּעֲיָא. וְאִי סָלְקָא דַּעְתָּךְ רַבִּי יְהוּדָה כְּרַבִּי עֲקִיבָא סְבִירָא לֵיהּ, מִכְּדִי חַיָּיבֵי לָאוִין לְרַבִּי עֲקִיבָא כְּחַיָּיבֵי כָרֵיתוֹת דְּמֵי, וְחַיָּיבֵי כָרֵיתוֹת לָאו בְּנֵי חֲלִיצָה וְיִבּוּם נִינְהוּ!
The Gemara infers: He switches the terms but does not dispute the halakha; but even Rabbi Yehuda agrees that if a priest marries a ḥalutza and then dies, she requires ḥalitza. And if it enters your mind that Rabbi Yehuda holds in accordance with the opinion of Rabbi Akiva, this poses a difficulty; after all, those liable for violating prohibitions, according to the opinion of Rabbi Akiva, are considered like those liable to receive karet, and those liable to receive karet are not capable of performing ḥalitza and levirate marriage, as the mitzva of levirate marriage does not apply to such relationships.
לִדְבָרָיו דְּתַנָּא קַמָּא קָאָמַר, וְלֵיהּ לָא סְבִירָא לֵיהּ.
The Gemara resolves the difficulty: Rabbi Yehuda does hold in accordance with the opinion of Rabbi Akiva, and as for his comment with regard to the definitions of a prohibition resulting from a mitzva and a prohibition stemming from sanctity, he merely stated his opinion in accordance with the statement of the first tanna; but he himself does not hold accordingly.
כִּי אֲתָא רַבִּי יִצְחָק, תָּנֵי כְּדִתְנַן: רַבִּי יְהוּדָה אוֹמֵר, אֵינוֹ חַיָּיב אֶלָּא מִשּׁוּם הָאֵם בִּלְבַד.
§ When Rav Yitzḥak came from Eretz Yisrael to Babylonia, he taught a baraita as we learned in the mishna: Rabbi Yehuda says: One who engages in intercourse with his mother who is also his father’s wife is liable to bring only one sin-offering, due to the fact that she is his mother, whether or not her marriage to his father was legitimate.
וְטַעְמָא מַאי? אָמַר אַבָּיֵי: דְּאָמַר קְרָא ״אִמְּךָ הִיא״. מִשּׁוּם אִמּוֹ אַתָּה מְחַיְּיבוֹ, וְאִי אַתָּה מְחַיְּיבוֹ מִשּׁוּם אֵשֶׁת אָב.
The Gemara asks: And what is the reason for this? Abaye says: It is because the verse states: “The nakedness of your father and the nakedness of your mother you shall not uncover: She is your mother; you shall not uncover her nakedness” (Leviticus 18:7). Rabbi Yehuda derives from this verse that you shall render him liable due to the fact that she is his mother, but you shall not render him liable to bring another sin-offering due to the fact that she is his father’s wife.
אֶלָּא מֵעַתָּה, ״עֶרְוַת אֵשֶׁת אָבִיךָ לֹא תְגַלֵּה עֶרְוַת אָבִיךָ הִיא״, מִשּׁוּם אֵשֶׁת אָב אַתָּה מְחַיְּיבוֹ, וְאִי אַתָּה מְחַיְּיבוֹ מִשּׁוּם אִמּוֹ?
The Gemara asks: If that is so, it should be derived from the verse: “The nakedness of your father’s wife you shall not uncover; it is your father’s nakedness” (Leviticus 18:8), that you shall render him liable due to the fact that she is his father’s wife, but you shall not render him liable due to the fact that she is his mother.
אֶלָּא אִמּוֹ שֶׁהִיא אֵשֶׁת אָבִיו, קָאֵי הָכָא וּמְמַעֵט לַהּ, קָאֵי הָכָא וּמְמַעֵט לַהּ. הַשְׁתָּא, אִמּוֹ שֶׁאֵינָהּ אֵשֶׁת אָבִיו – מִיחַיַּיב, אֵשֶׁת אָבִיו שֶׁאֵינָהּ אִמּוֹ – מִיחַיַּיב, אִמּוֹ שֶׁהִיא אֵשֶׁת אָבִיו – לָא מִיחַיַּיב כְּלָל?
But if so, with regard to one’s mother who is his father’s wife, it is found that the verse stands, i.e., is written, here, with regard to intercourse with one’s mother, and excludes liability due to the fact that she is his father’s wife, and stands there, with regard to intercourse with one’s father’s wife, and excludes liability due to the fact that she is his mother. The result now is that for his mother who is not his father’s wife he is rendered liable, and for his father’s wife who is not his mother he is rendered liable, but for his mother who is his father’s wife he is not rendered liable at all, which seems absurd.
וְתוּ, לְרַבָּנַן נָמֵי, הָכְתִיב ״אִמְּךָ הִיא״? אֶלָּא, הָהוּא מִיבְּעֵי לֵיהּ לְכִדְרַב שִׁישָׁא בְּרֵיהּ דְּרַב אִידִי. לְרַבִּי יְהוּדָה נָמֵי, הָהוּא מִיבְּעֵי לֵיהּ לְכִדְרַב שִׁישָׁא בְּרֵיהּ דְּרַב אִידִי.
And furthermore, according to the Rabbis too, who disagree with Rabbi Yehuda and hold that one who engages in intercourse with his mother who is married to his father is liable to bring two sin-offerings, isn’t the verse: “She is your mother,” written; i.e., how do they explain this verse? Rather, that phrase is necessary for the halakha derived from it by Rav Sheisha, son of Rav Idi, as the Gemara will soon explain (54a). Therefore, according to Rabbi Yehuda as well, that phrase is necessary for the halakha derived by Rav Sheisha, son of Rav Idi, and Rabbi Yehuda’s opinion in the mishna cannot be derived from it.
אֶלָּא אָמַר רַב אַחָא בְּרֵיהּ דְּרַב אִיקָא: אָמַר קְרָא ״עֶרְוָתָהּ״, מִשּׁוּם עֶרְוָה אַחַת אַתָּה מְחַיְּיבוֹ, וְאִי אַתָּה מְחַיְּיבוֹ מִשּׁוּם שְׁתֵּי עֲרָיוֹת.
Rather, Rav Aḥa, son of Rav Ika, says that there is a different source for Rabbi Yehuda’s opinion: The verse states: “You shall not uncover her nakedness [ervatah],” in the singular form, from which it is derived that you shall render him liable for one forbidden sexual relationship [erva], but you shall not render him liable for two types of forbidden sexual relationships.
אֶלָּא מֵעַתָּה: ״עֶרְוַת כַּלָּתְךָ לֹא תְגַלֵּה אֵשֶׁת בִּנְךָ הִיא לֹא תְגַלֶּה עֶרְוָתָהּ״ – הָכִי נָמֵי מִשּׁוּם עֶרְוָה אַחַת אַתָּה מְחַיְּיבוֹ וְאִי אַתָּה מְחַיְּיבוֹ מִשּׁוּם שְׁתֵּי עֲרָיוֹת?
The Gemara asks: If that is so, then from the verse: “You shall not uncover the nakedness of your daughter-in-law; she is your son’s wife, you shall not uncover her nakedness” (Leviticus 18:15), should it also be derived that you shall render him liable for one forbidden sexual relationship, but you shall not render him liable for two types of forbidden sexual relationships?
וְהָתְנַן: הַבָּא עַל כַּלָּתוֹ חַיָּיב עָלֶיהָ מִשּׁוּם כַּלָּתוֹ וּמִשּׁוּם אֵשֶׁת אִישׁ, בֵּין בְּחַיֵּי בְנוֹ בֵּין לְאַחַר מִיתַת בְּנוֹ, וְלָא פְּלִיג רַבִּי יְהוּדָה.
But didn’t we learn in the mishna: One who engages in intercourse with his daughter-in-law is liable to bring two sin-offerings for his intercourse with her: One due to the prohibition against engaging in intercourse with one’s daughter-in-law, and one due to the prohibition against engaging in intercourse with a married woman; the former liability applies both during his son’s lifetime and after his son’s death. And Rabbi Yehuda does not dispute this halakha.
אֶלָּא, כֵּיוָן דְּחַד גּוּפָא הוּא, אַף עַל גַּב דִּתְרֵי אִיסּוּרֵי נִינְהוּ, כְּתִיב ״עֶרְוָתָהּ״. הָכָא נָמֵי, כֵּיוָן דְּחַד גּוּפָא הוּא, אַף עַל גַּב דִּתְרֵי אִיסּוּרֵי נִינְהוּ, כְּתִיב ״עֶרְוָתָהּ״.
Rather, it must be explained that since the daughter-in-law has one body, although engaging in intercourse with her involves two prohibitions, the term “her nakedness [ervatah],” in the singular, is written. Here too, with regard to one’s father’s wife, since she has one body, although there are two prohibitions, the term “her nakedness [ervatah]” is written.
אֶלָּא אָמַר רָבָא: קָסָבַר רַבִּי יְהוּדָה ״עֶרְוַת אָבִיךָ״ – זוֹ אֵשֶׁת אָבִיךָ, וּמַיְיתֵי לַהּ בִּגְזֵירָה שָׁוָה.
Rather, Rava says that there is an alternative source for Rabbi Yehuda’s opinion: Rabbi Yehuda holds that concerning the meaning of the phrase “the nakedness of your father,” this is referring to your father’s wife. And he derives this interpretation by means of a verbal analogy from the verse: “And the man who lies with his father’s wife, he has uncovered his father’s nakedness” (Leviticus 20:11).
וּמַשְׁמַע, בֵּין אֵשֶׁת אָבִיו שֶׁהִיא אִמּוֹ בֵּין אֵשֶׁת אָבִיו שֶׁאֵינָהּ אִמּוֹ. אִמּוֹ שֶׁאֵינָהּ אֵשֶׁת אָבִיו מִנַּיִין? תַּלְמוּד לוֹמַר: ״עֶרְוַת אִמְּךָ לֹא תְגַלֵּה אִמְּךָ הִיא״. מִשּׁוּם אִמּוֹ אַתָּה מְחַיְּיבוֹ, וְאִי אַתָּה מְחַיְּיבוֹ מִשּׁוּם אֵשֶׁת אָבִיו.
And the Torah indicates that she is forbidden whether she is his father’s wife who is his mother or whether she is his father’s wife who is not his mother. From where is it derived that one who engages in intercourse with his mother who is not his father’s wife is liable? The verse states subsequently: “The nakedness of your mother you shall not uncover.” And from the ensuing phrase: “She is your mother,” it is derived that in a case where his mother is also his father’s wife, you shall render him liable due to the fact that she is his mother, but you shall not render him liable due to the fact that she is his father’s wife.
