Fifteen women release their co-wives, and their co-wives' co-wives, from chalitzah and from yibum, ad infinitum. They are the follow- ing: A [man's] daughter, daughter's daughter, and son's daughter; his wife's daughter, her son's daughter, and her daughter's daughter; his mother-in-law, mother-in-law's mother, and father-in-law's mother; his maternal sister, mother's sister, wife's sister, maternal brother's wife, the wife of his noncontemporaneous brother, and his daughter-in-law. These release their co-wives and their co-wives' co-wives from chalitzah and from yibum, ad infinitum.  If any of these died, refused, was divorced, or was found to be an ailonis, their co-wives are permitted. [However,] one cannot say of his mother-in-law, or mother-in-law's mother, or father-in-law's mother, that they were found to be an ailonis or that they refused.

How do they release their co-wives? [If] a [man's] daughter, or [any] one of these forbidden relations, was married to his brother, and he had another wife [as well], and he died —- just as his daughter is released, so too is her co-wife. If his daughter's co-wife went and married his second brother, and he [also] had another wife, and [then] he died —- just as his daughter's co-wife is released, so too is her co-wife's co-wife, even if there are a hundred.  How is it that if they died their co-wives are permitted? [If] a [man's] daughter, or [any] one of these forbidden relatives, was married to his brother, and he [also] had another wife, and his daughter died, or was divorced, and then his brother died —- her co-wife is permitted.  Anyone who was able to refuse but did not do so —- her co-wife requires chalitzah but is prohibited from yibum.

Six forbidden relations are more stringent than these, for they are married to others —- their co-wives are permitted: his mother, father's wife, father's sister, paternal sister, father's brother's wife, and paternal brother's wife.

Beis Shammai permit the co-wives to the brothers, but Beis Hillel forbid [them]. [If] they performed chalitzah —- Beis Shammai disqualify [them] from [marrying into] the priesthood, but Beis Hillel qualify [them]. [If] they were taken in yibum —- Beis Shammai qualify [them], but Beis Hilel disqualify [them].  Even though these prohibited and these per-mitted, these disqualified and these qualified —- Beis Shammai did not refrain from marrying women of Beis Hillel, nor Beis Hillel of Beis Shammai.  [Despite] all the things that these judged tahor and that these judged tamei, they did not refrain from using each other's utensils for [purposes of] taharah.

How does the wife of his noncontemporaneous brother [release her co-wives]? [There were] two brothers, one of whom died, and [then another] brother was born; subsequently, the second one performed yibum with his brother's widow and died —- the first is discharged as the wife of his noncontemporaneous brother, and the second as her co-wife. [If] he performed maamar with her and then died —- the second requires chalitzah but may not be taken in yibum.

[If there were] two brothers, and one of them died, and the second [then] performed yibum with his brother's widow; subsequently, another brother was born, and then he died —- the first is discharged as the wife of his non-contemporaneous brother, and the second as her co-wife.  [If] he performed maamar with her and [then] died —- the second requires chalitzah but may not be taken in yibum. R' Shimon says: He may perform yibum with whichever of them he wishes, or perform chalitzah with whichever of them he wishes.

A general principle was stated concerning the yevamah: Anyone prohibited because of ervah neither performs chalitzah nor is taken in yibum. [If] her prohibition is by commandment or because of sanctity, she requires chalitzah but may not be taken in yibum.  [If] her sister is her [fellow] yevamah, she may either perform chalitzah or be taken in yibum.

Prohibitions by commandment [are] —- secondary [arayos] by Rabbinical decree. Prohibitions because of sanctity [are] —- a widow to a Kohen Gadol; a divorcee or a chalutzah to an ordinary Kohen; a mamzeress or Nesinite to a Yisrael; and the daughter of a Yisrael to a Nesinite or mamzer.

One who has a brother of any kind binds his brother's wife for yibum, and is [considered] his brother in all respects; except for someone who has [a brother] from a slave-woman or a non-Jewess.  One who has a son of any kind releases his father's wife from yibum, is liable for striking or cursing him, and is considered his son in every respect; except for someone who has [a son] from a slave-woman or a non-Jewess.

One who betrothed one of two sisters, but does not know which of them he betrothed, [must] divorce each of them. [If] he died and left one brother, he performs chalitzah with both. [If] he left two [brothers], one performs chalitzah and the other [may then] perform yibum. [However, if] they went ahead and married [them], we do not force them to divorce.