The nakedness of the wife of the brother of your father, you shall not reveal: Not to have intercourse with the wife of the brother of your father. And this one is called his aunt (dodah) in Scripture, since she is the wife of his uncle (dod), as it is stated (Leviticus 18:14), “to his wife you shall not approach, she is your aunt (dodah).” And this warning is from when she was betrothed to his uncle — meaning to say, she was designated for him — and there is no need to say, after she married him. And [this is the case] whether [it is] in the lifetime of his uncle and even after he divorced her, or whether after his death (Yevamot 97a).
The laws of the commandment: For example, that which they, may their memory be blessed, said (Yevamot 54b) that he is called the brother of his father regarding this prohibition of his wife when he is the brother of his father from the father’s side. But the brother of the father from the mother’s side is not [included] in this prohibition of “to his wife you shall not approach” by Torah writ. However the Sages made a fence and forbade even the wife of the brother of his father from the mother’s side, in order to distance us greatly so as not to touch a prohibition of the Torah. And likewise they also forbade the wife of the brother of his mother — whether she is a sister from the father’s side alone or from the mother’s side alone. And even though the wife of the brother of his mother is not forbidden at all from Torah writ; since the Torah forbade the wife of the brother of his father from the side of the father — who is called “his uncle” — they added upon the prohibition to make a fence with all of these that are similar to it.
And this prohibition is practiced in every place and at all times. And [in the case of] one who transgresses it and laid with the wife of the brother of his father from the father’s side, during the lifetime of his uncle, volitionally — and there were witnesses — the death of both of them is with strangulation, as this is the law of the one who has intercourse with a married woman, with strangulation. And if he laid with her volitionally after the death of his uncle, he is liable for excision; and if there are witnesses, he is lashed; inadvertently, he brings a fixed sin-offering — as it is well-known to us that with anything for which there is excision if volitional, its inadvertent transgression is with a sin-offering. And if he laid with the wife of the brother of his father from the mother’s side or the wife of the brother of the mother — whether from the father’s side or from the mother’s side — we strike him with lashes of rebellion when volitional, and he is exempt when inadvertent.
עֶרְוַת אֵשֶׁת אֲחִי אָבִיךָ לֹא תְגַלֵּה – שֶׁלֹּא לָבוֹא עַל אֵשֶׁת אֲחִי הָאָב, וְזֹאת נִקְרֵאת בַּכָּתוּב דּוֹדָתוֹ לְפִי שֶׁהִיא אֵשֶׁת דּוֹדוֹ, שֶׁנֶּאֱמַר (ויקרא יח יד) אֶל אִשְׁתּוֹ לֹא תִקְרָב דֹּדָתְךָ הִיא. וְאַזְהָרָה זוֹ הִיא מִכֵּיוָן שֶׁנִּתְאָרְסָה לְדוֹדוֹ, כְּלוֹמַר, שֶׁנִּתְקַדְּשָׁה לוֹ, וְאֵין צָרִיךְ לוֹמַר אַחַר שֶׁנִּשֵּׂאת לוֹ, וּבֵין בְּחַיֵּי דּוֹדוֹ וַאֲפִילּוּ גֵּרְשָׁהּ, וּבֵין אַחַר מִיתָתוֹ (יבמות צז א).
The nakedness of the wife of the brother of your father, you shall not reveal: Not to have intercourse with the wife of the brother of your father. And this one is called his aunt (dodah) in Scripture, since she is the wife of his uncle (dod), as it is stated (Leviticus 18:14), “to his wife you shall not approach, she is your aunt (dodah).” And this warning is from when she was betrothed to his uncle — meaning to say, she was designated for him — and there is no need to say, after she married him. And [this is the case] whether [it is] in the lifetime of his uncle and even after he divorced her, or whether after his death (Yevamot 97a).
מִשָּׁרְשֵׁי הַמִּצְוָה. כָּתַבְנוּ לְמַעְלָה (מצוה קצ).
We have written above about the roots of the commandment (Sefer HaChinukh 190).
דִּינֵי הַמִּצְוָה. כְּגוֹן מַה שֶׁאָמְרוּ זִכְרוֹנָם לִבְרָכָה (יבמות נד, ב), שֶׁאֲחִי אָבִיו נִקְרָא לְעִנְיַן אִסּוּר זֶה שֶׁל אִשְׁתּוֹ כְּשֶׁהוּא אֲחִי אָבִיו מִצַּד אָב, אֲבָל אֲחִי אָבִיו מִצַּד אֵם אֵינוֹ בְּאִסּוּר זֶה שֶׁל אֶל אִשְׁתּוֹ לֹא תִקְרָב מִדִּין תּוֹרָה, אֶלָּא שֶׁחֲכָמִים גָּדְרוּ גָּדֵר וְאָסְרוּ אֲפִלּוּ אֵשֶׁת אֲחִי אָבִיו מִצַּד אֵם, כְּדֵי לְהַרְחִיקֵנוּ הַרְבֵּה שֶׁלֹּא לִגַּע לְאִסּוּר תּוֹרָה. וְכֵן אָסְרוּ גַּם כֵּן אֵשֶׁת אֲחִי אִמּוֹ, בֵּין שֶׁהוּא אָחִיהָ מִצַּד אָב לְבַד אוֹ מִצַּד אֵם לְבַד, וְאַף עַל פִּי שֶׁאֵשֶׁת אֲחִי אִמּוֹ אֵינָהּ אֲסוּרָה כְּלָל דְּבַר תּוֹרָה, מִפְּנֵי שֶׁאָסְרָה הַתּוֹרָה אֵשֶׁת אֲחִי אָבִיו מִצַּד אָב שֶׁנִּקְרָא דּוֹדוֹ, הוֹסִיפוּ הֵם בְּאִסּוּר לְגֶדֶר כָּל אֶחָד מֵאֵלּוּ הַדּוֹמִים לוֹ.
The laws of the commandment: For example, that which they, may their memory be blessed, said (Yevamot 54b) that he is called the brother of his father regarding this prohibition of his wife when he is the brother of his father from the father’s side. But the brother of the father from the mother’s side is not [included] in this prohibition of “to his wife you shall not approach” by Torah writ. However the Sages made a fence and forbade even the wife of the brother of his father from the mother’s side, in order to distance us greatly so as not to touch a prohibition of the Torah. And likewise they also forbade the wife of the brother of his mother — whether she is a sister from the father’s side alone or from the mother’s side alone. And even though the wife of the brother of his mother is not forbidden at all from Torah writ; since the Torah forbade the wife of the brother of his father from the side of the father — who is called “his uncle” — they added upon the prohibition to make a fence with all of these that are similar to it.
וְנוֹהֵג אִסּוּר זֶה בְּכָל מָקוֹם וּבְכָל זְמַן. וְהָעוֹבֵר עָלֶיהָ וְשָׁכַב אֶת אֵשֶׁת אֲחִי אָבִיו מִצַּד אָב בְּחַיֵּי דּוֹדוֹ בְּמֵזִיד וְיֵשׁ עֵדִים, מִיתַת שְׁנֵיהֶם בְּחֶנֶק, שֶׁכֵּן הוּא הַדִּין הַבָּא עַל אֵשֶׁת אִישׁ בְּחֶנֶק, וְאִם שָׁכַב אוֹתָהּ אַחֲרֵי מוֹת דּוֹדוֹ, בְּמֵזִיד חַיָּב כָּרֵת, וְאִם יֵשׁ עֵדִים לוֹקֶה, בְּשׁוֹגֵג מֵבִיא חַטָּאת קְבוּעָה, כְּמוֹ שֶׁיָּדוּעַ לָנוּ דְּכָל שֶׁבִּזְדוֹנוֹ כָּרֵת בְּשִׁגְגָתוֹ חַטָּאת. וְאִם שָׁכַב אֶת אֵשֶׁת אֲחִי אָבִיו מִצַּד אֵם, אוֹ אֶת אֵשֶׁת אֲחִי אִמּוֹ, בֵּין מִצַּד אָב אוֹ מִצַּד אֵם, בְּמֵזִיד מַכִּין אוֹתוֹ מַכַּת מַרְדּוּת, בְּשׁוֹגֵג פָּטוּר.
And this prohibition is practiced in every place and at all times. And [in the case of] one who transgresses it and laid with the wife of the brother of his father from the father’s side, during the lifetime of his uncle, volitionally — and there were witnesses — the death of both of them is with strangulation, as this is the law of the one who has intercourse with a married woman, with strangulation. And if he laid with her volitionally after the death of his uncle, he is liable for excision; and if there are witnesses, he is lashed; inadvertently, he brings a fixed sin-offering — as it is well-known to us that with anything for which there is excision if volitional, its inadvertent transgression is with a sin-offering. And if he laid with the wife of the brother of his father from the mother’s side or the wife of the brother of the mother — whether from the father’s side or from the mother’s side — we strike him with lashes of rebellion when volitional, and he is exempt when inadvertent.