פירוש על יבמות 2:4

שניות – [secondary grade of forbidden relationships seen as incestuous] – forbidden incestuous or adulterous sexual relationships that the Scribes/Soferim decreed upon them which are called prohibitions resulting from a Mitzvah (i.e., based upon the Mitzvah not to deviate from the rulings of the Sages – see Deuteronomy 17:11), for it is a Mitzvah to hearken to the words of the Sages, and which are they? The mother of his mother, and there is no limitation but if it is the father of his mother alone, and the mother of his father, and it has no limitation [and if the father of his father] and the wife of his father’s father, and it has no limitation, and the wife of his mother’s father alone, and the wife of his brother’s father from the mother, and the wife of his mother’s brother, whether from the mother or whether from the father and there is no limitation, and daughter-in-law of his daughter, and the daughter of his son’s daughter and the daughter of the daughter’s daughter and the daughter of’s his son’s son and the daughter of his son’s daughter, and the daughter [of the daughter] of the son of his wife, and the daughter [of the daughter] of his wife’s daughter, and the mother of the mother of his father’s wife, and the mother of [the mother] of his wife’s mother, and the father of the mother of his wife’s mother, and the mother of the father of his father’s wife.

Introduction Mishnah four defines the two categories mentioned in section two of mishnah three.

A “prohibition due to a commandment” [refers to] the secondary incest prohibitions forbidden by the scribes. “A prohibition due to holiness” [refers to the following forbidden relationships]: a widow to a high priest; a divorced woman, or one that had performed halitzah to a regular priest; a mamzereth or a netinah to an Israelite; and an Israelite woman to a natin or a mamzer. Women who are not themselves forbidden because of incest laws, but the scribes (rabbis) decreed that they were nevertheless prohibited are called “secondary incest prohibitions”. Some examples of “secondary incest prohibitions” are one’s grandmother and one’s son’s or daughter’s daughter-in-law. The reason that the rabbis prohibited these women is to keep people away from potential sin. That is to say, if it became permitted to have relations with your son’s daughter-in-law, you might think that relations with one’s own daughter-in-law are also prohibited. These prohibitions are called “prohibitions due to commandments” due to the commandment to obey the words of the sages.

גרושה וחלוצה לכהן הדיוט – such as, for example, that he (i.e., as a Kohen) transgressed his dead brother and had married a divorcee or a woman who had undergone Halitzah, and when he died, she needs Halitzah for Kiddushin/betrothal takes effect in those liable for violating negative commandments, but not levirate marriage, for she is prohibited to him, but to exempt/free her without anything is impossible, for it is not strong to release her, for we derive “her” from the wife’s sister, which is punishable by extirpation.

“Prohibitions due to holiness” are prohibitions that are not due to incest (or adultery) but rather to the sanctity of the priests (see Leviticus 21:6-7) or the sanctity of the people of Israel. A widow to a high priest: If a widow becomes liable for yibbum to a high priest, he must perform halitzah for her. He cannot have yibbum with her because she is prohibited to him (Leviticus 21:14). A divorced woman or one that had performed halitzah to a regular priest: If a previously divorced woman or a woman who had halitzath, should become liable for yibbum with a regular priest, she must perform halitzah and cannot have yibbum, since she is prohibited to him (Leviticus 21:7). Note that this situation will usually not happen because a divorced woman or one who had halitzah cannot marry a priest, and therefore, she should not have married the yavam’s (who is a priest) brother, who is also a priest. Nevertheless, if the brother transgressed and did marry a divorcee (marriage between a priest and a divorcee is prohibited but valid), and then died, the divorcee (who is now also a widow) has halitzah with the brother but not yibbum. A mamzereth or a netinah to an Israelite and an Israelite woman to a natin or a mamzer: A mamzer (or mamzereth, a female mamzer) is the child of a forbidden union (Deuteronomy 23:3. The definition of a mamzer appears in chapter 4:13). A natin (or a netinah, a female natin) is a descendent of a tribe of foreigners who converted through trickery in the days of Joshua and were declared temple slaves (Joshua 9:27). Neither of these categories of men or women can marry full Israelites. Therefore, if one of these people becomes liable to have yibbum with an Israelite, or if an Israelite becomes liable to have yibbum with one of them, they have halitzah and not yibbum.