Misva #191: To Not Reveal the Nakedness of the Wife of the Father, even though she is not his mother

The Torah in Parashat Ahareh-Mot (Vayikra 18:8) commands that one may not “reveal the nakedness” of – meaning, engage in intercourse with – one’s father’s wife. A separate prohibition forbids engaging in relations with one’s mother; this command forbids intercourse with one’s father’s wife even if she is not the person’s mother. The Sefer Ha’hinuch explains that in addition to the reasons for the other prohibitions of Arayot (forbidden relations with one’s relatives), this command is also aimed at maintaining respect for one’s father. Having relations with a woman who is or was married to one’s father is very disrespectful to the father, and so the Torah forbids having such a relationship. This prohibition applies even after the father divorced the woman, and even after he has died. Once a man marries a woman, his sons may never engage in intercourse with her at any point thereafter. This command applies even to a woman whom the father had only betrothed, and has yet to marry. Although the father has not had any physical relationship with the woman, as he had only betrothed her (such as by giving her a ring and declaring that she is thereby betrothed to him), his sons may not engage in relations with her at any point thereafter. It should be noted that the prohibition of “Eshet Ab” (having relations with one’s father’s wife) is binding even upon gentiles – like all prohibitions of Arayot – but for them, this prohibition applies only once the father consummated the marriage. Whereas a Jew may not have relations with a woman whom his father had merely betrothed, without consummating the marriage, a gentile is permitted to have relations with a woman whom his father betrothed but had yet to have a physical relationship with. The Sages expanded this prohibition, forbidding relations also with the wife of one’s father’s father. One may not engage in relations with a woman whom his grandfather had married, even if they are no longer married, and even if the grandfather had died. This applies also to the grandfather’s father, and his father, etc. The Sages also forbade relations with the wife of one’s mother’s father. However, they did not extend this prohibition to include even that grandfather’s father, and prior generations. The Sefer Ha’hinuch explains that the Torah prohibition which the Sages sought to safeguard was that of “Eshet Ab” – one’s father’s wife – so they expanded the prohibition to include one’s father’s father and all prior generations, but not for all prior generations of one’s mother’s father. Relations with these “Sheniyot” (“secondary” relatives), which are forbidden by force of Rabbinic enactment, are permissible for gentiles. They are bound only by the Biblical laws of Arayot, and not by the Rabbis’ expansion of these prohibitions. The prohibition of “Eshet Ab” applies at all times, and in all places. One who had intercourse with his father’s wife is liable to Karet (external excision from the Jewish Nation), and if there are witnesses to the act, then he is liable to Sekila (execution by stoning). One who committed this violation unintentionally must bring a Hatat (sin-offering). A person who had relations with any of the “Sheniyot” – relatives with whom relations are forbidden by force of Rabbinic enactment – is liable to Malkut for violating the Rabbis’ decree.