Issurei Biah - Chapter Two

The [following] four women: the wife of a man's father, the wife of his son, the wife of his brother, and the wife of the brother of his father, are considered an ervah1 for him forever, whether after consecration or after marriage, in the lifetime of their husbands or after their deaths, [even] if they were divorced - with the exception of the wife of one's brother who did not leave a son.2

If a man engages in relations with one of these woman during the lifetime of their husbands, he is liable for two [sin-offerings3]: for incestuous relations and adulterous relations, for both of these prohibitions take effect at the same time.4

Therefore a person who engages in relations with his mother who is his father's wife is liable for two [sin-offerings], one because [the woman is] his mother and one because she is his father's wife. [This applies] both during his father's lifetime and after his father's death.5

The wives of both a person's paternal brother and his maternal brother are considered an ervah for him. [This applies regardless if he and/or his brother were conceived] in marriage or in a promiscuous relationship.6 The wife of the maternal brother of a man's father is, however, forbidden [only] as a shniyah, as explained.7 Both a person's paternal sister and his maternal sister are considered an ervah for him. [This applies regardless if he and/or his sister were conceived] in marriage or in a promiscuous relationship, e.g., his mother or his father acted promiscuously with others and his sister was conceived promiscuously, as [implied by Leviticus 18:9]: "one born at home or one born beyond [marriage]."

The daughter of his father's wife who is his paternal sister is an ervah for him, [as ibid.:11] states: "the nakedness of the daughter of your father's wife, your father's offspring." If, however, a man's father marries a woman and she has a daughter from another man, that daughter is permitted to him.8 She is not "your father's offspring." Behold one is already liable for [relations] with her because she is a sister, why then [does the Torah mention]: "the daughter of your father's wife"? So that one should be liable for this prohibition as well.9

Therefore a man who engages in relations with his sister who was born to his father's wife in marriage is liable for two [sin offerings]: one because of "the nakedness of your sister" and one because of "the nakedness of the daughter of your father's wife." If, however, one's father raped or seduced a woman and conceived a daughter, one is liable only for having relations with one's sister. For the daughter of the woman who was raped is not the daughter of the wife of one's father.10

The sister of his mother is considered an ervah for him. [This applies to both her paternal and maternal sister and applies regardless whether she [was conceived] in marriage or in a promiscuous relationship. Similarly, his father's sister - both his paternal and maternal sister, whether she [was conceived] in marriage or in a promiscuous relationship - is considered an ervah for him.

When a person has promiscuous relations with a woman and conceives a daughter with her, that daughter is considered an ervah for him.11 Although the Torah does not state: "Do not reveal the nakedness of your daughter," the prohibition is of Scriptural origin. Since [the Torah] forbade [relations] with the daughter of one's daughter, it did not mention [the prohibition against] one's daughter. This is not from the words of our Sages.12 Therefore a person who has relations with a daughter born of his wife is liable for two [sin offerings],13 for [relations with] his daughter and for relations with a woman and her daughter.14

When a person consecrates a woman, her close relatives - six women - become forbidden to him as an ervah forever. This applies whether he consummates [the bond through nisuin] or divorces her, in the lifetime of his wife and after her death. They are: a) her mother, b) her mother's mother, c) her father's mother, d) her daughter,15 e) her daughter's daughter, and f) her son's daughter. If he has relations with one of these women during the lifetime of his wife, both [he and she] are executed by burning.

If he has relations with one of these women after his wife's death, they are liable for kerait,16 but they are not executed by the court, as [derived from Leviticus 20:14]: "In fire, he and they shall be burnt." [This implies17 that only] when both women - his wife and the woman with whom he had relations - are alive, he and the ervah are executed by burning. When both [women] are not alive, there is no execution by burning.18

Similarly, the sister of his wife is considered an ervah for him until his wife dies.19 Both her maternal sister and her paternal sister, whether conceived in marriage or promiscuously, are considered as an ervah for him.

If a man transgressed and engaged in relations with one of these seven women, whether intentionally or inadvertently, although he and the woman are liable for execution by the court or kerait, he is not forbidden to engage in relations with his wife.20 The only exception is [when he engages in relations with] the sister of the woman he consecrated. In this instance, his wife is forbidden to him, as explained in Hilchot Gerushin.21

When a man engages in promiscuous relations with a woman, the seven relatives mentioned above are not forbidden to him [according to Scriptural Law].22 Nevertheless, our Sages23 prohibited anyone who had promiscuous relations with a woman from marrying one of these seven relatives during the promiscuous woman's lifetime.24 [The rationale is that] the promiscuous woman will come to visit her relatives. He will thus enter into solitude with her. [Since] he is familiar with her, we fear that they will transgress and thus he will engage in relations with an ervah.25

Even if a man is merely suspected of relations with a woman,26 he should not marry one of her relatives until the woman with whom he was suspected of having relations died. If, however, he married the relative of the woman with whom he was suspected of having relations, he should not divorce her.

When a person was suspected of having relations with an ervah or a rumor to that effect was circulated, he should not dwell together with her in the same lane or appear in the same neighborhood.27 An incident occurred concerning a man who was rumored [to have engaged in relations] with his mother-in-law and our Sages had him beaten28 because he passed by the entrance to her home.

When a person has promiscuous relations with a woman and her daughter or a woman and her sister or the like, it is as if he had relations with two unrelated woman. One is considered an ervah because of the other only in the instance of marriage, not in an instance of promiscuity. Similarly, if a man's father, son, brother, or father's brother raped a woman or seduced her, she is permitted to him and he may marry her. [The prohibition involving these individuals] mentions "the wife of" and here there is no context of marriage.

When a man's father or son marries a woman, that man may marry her daughter or her mother as we explained.29 A person may marry the wife of his brother's son.30 A man may marry a woman and her sister's daughter or her brother's daughter at the same time. It is a mitzvah from the Sages for a man to marry his sister's daughter,31 as [alluded to by Isaiah 58:7]: "Do not turn away from your own flesh." This law also applies to his brother's daughter.32