Rif Yevamot 8a {27a continues; 26a; 28b - 29a; 30a}

8a

{27a continues}

דהויא יבמה שהותרה ונאסרה וחזרה והותרה תחזור להיתרה הראשון
ורבי יוחנן אמר מתה שניה מותר בראשונה אבל מתה ראשונה אסור בשניה מאי טעמא דכל יבמה שאין אני קורא בה בשעת נפילה יבמה יבא עליה הרי היא כאשת אח שיש לה בנים ואסורה ורב הני מילי היכא דקאי באפה איסור אחות אשה דאורייתא אבל הכא זיקה דרבנן היא וקי"ל כר' יוחנן דכל רב ורבי יוחנן הלכה כרבי יוחנן

For she is a yevama who was permitted, then became forbidden, and then returned to being permitted, and so she returns to her original permittedness.
And Rabbi Yochanan said: If the second one died, he is permitted to the first one, but if the first one died, he is forbidden to the second one.
What is the reason? For any yevama who I cannot apply to her at the time of her falling {to yibbum} the verse {Devarim 25:5}

ה כִּי-יֵשְׁבוּ אַחִים יַחְדָּו, וּמֵת אַחַד מֵהֶם וּבֵן אֵין-לוֹ--לֹא-תִהְיֶה אֵשֶׁת-הַמֵּת הַחוּצָה, לְאִישׁ זָר: יְבָמָהּ יָבֹא עָלֶיהָ, וּלְקָחָהּ לוֹ לְאִשָּׁה וְיִבְּמָהּ.

5 If brethren dwell together, and one of them die, and have no child, the wife of the dead shall not be married abroad unto one not of his kin; her husband's brother shall go in unto her, and take her to him to wife, and perform the duty of a husband's brother unto her.

she is just like the sister of a brother who has children, and she is forbidden.
And Rav? These words are where what stands to her face is the Biblical prohibition of his sister's wife, but here, it is merely a Rabbinic levirate bond.
And we establish like Rabbi Yochanan, for any dispute between Rav and Rabbi Yochanan, the halacha is like Rabbi Yochanan.

{Yevamot 26a}
Mishna:

היתה אחת מהן אסורה על זה איסור ערוה אסור בה ומותר באחותה והשני אסור בשתיהן
איסור מצוה ואיסור קדושה חולצות ולא מתיבמות
היתה אחת מהן אסורה על זה איסור ערוה והשניה אסורה על זה איסור ערוה האסורה לזה מותרת לזה והאסורה לזה מותרת לזה וזו היא שאמרו אחותה שהיא יבמתה או חולצת או מתיבמת:

If one of them {the sisters} was forbidden on this one {of the two yavam brothers} as a Biblically forbidden relation {of ervah} he is forbidden to her and permitted to her sister {since the first sister is not a candidate and thus the second sister is not considered the sister of one two whom he has a levirate bond}, and the second {brother} is forbidden to both of them {for each is achot zekukato}.
If a prohibition of {Rabbinic} precept of a prohibition of holiness {such as a kohen marrying a divorcee} they undergo chalitza and not yibbum.
If one {sister} was forbidden on this one {brother} as a Biblical prohibition {of erva}, and the second one {sister} was forbidden on that one {other brother} as a Biblical prohibition {of erva}, the one forbidden to this one is permitted to that one, and the one forbidden to that one is permitted to this one. And this is what they said "her sister who is her sister-in-law may either undergo chalitza or yibbum."

{Yevamot 28b}

ג' אחין ב' מהם נשואין שתי אחיות או אשה ובתה או אשה ובת בתה או אשה ובת בנה ומתו הנשואין את האחיות הרי אלו חולצות ולא מתיבמות ורבי שמעון פוטר
היתה אחת מהן אסורה עליו איסור ערוה אסור בה ומותר באחותה איסור מצוה ואיסור קדושה חולצות ולא מתיבמות

Three brothers, two of whom married two sisters, or a woman and her daughter, or a woman and her daughter's daughter, or a woman and her son's daughter, and the ones who married the sisters {et al} died, they {the widows} undergo chalitza and not yibbum.
And Rabbi Shimon exempts {them from chalitza}.
If one of them {the widows} was forbidden to him as a Biblical prohibition {of erva}, he is forbidden to her and permitted to her sister. If she was forbidden to him as a prohibition of {Rabbinic} precept of a {Biblical} prohibition of holiness {such as a kohen to a divorcee} she undergoes chalitza and not yibbum.

{Yevamot 29a}

שלשה אחין שנים מהן נשואין שתי אחיות ואחד מופנה ומת אחד מבעלי אחיות ועשה בה מופנה מאמר ואחר כך מת אחיו השני ב"ש אומרים אשתו עמו והלה תצא משום אחות אשה ובית הלל אומרים מוציא את אשתו בגט ובחליצה ואשת אחיו בחליצה וזו היא שאמרו אי לו על אשתו ואי לו על אשת אחיו

Three brothers, two of whom are married to two sisters, and one of them is unmarried, and one of the husbands of the sisters died, and the unmarried brother performs maamar {Rabbinic betrothal of a yevama}, and afterwards, the second {of the two initially married brothers} died: Bet Shammai say his wife is with him {=the one upon whom maamar was performed he keeps}, and the other one goes out because of the sister of his wife.
And Bet Hillel say that he sends his wife {the one upon he performed maamar but not yet yibbum} with a bill of divorce and with chalitza, and his brother's wife with chalitza. And this is what they say: "Oy to him upon his wife and oy to him on his brother's wife!"

{Yevamot 30a}

ג' אחין ב' מהן נשואין שתי אחיות ואחד נשוי נכרית ומת א' מבעלי אחיות וכנס נשוי נכרית את אשתו ומת השניה יוצאת משום אחות אשה והראשונה משום צרתה עשה בה מאמר ומת נכרית חולצת ולא מתיבמת

Three brothers, two of whom married two sisters, and one married a stranger {that is, not a sister to the other two}, and then one of the husbands of the sisters died, and the one who married a stranger married his wife {widow, thus making this yevama a rival to the stranger} and then he {the brother who married the stranger} died {leaving two yevamot, one his first wife who is the "stranger" and the second his brother's wife who he took as a yevama} -- the second one {=the widow of his brother} goes out because of his wife's sister {since this remaining brother is married to her sister} and the first one {the stranger} because of being her rival.
If he {this brother who initially married the stranger} performed maamar {Rabbinic betrothal on a yevama, rather than full yibbum} and then died {leaving the stranger and the sister}, the stranger undergoes chalitza and not yibbum.

Gemara:

וה"ה אע"ג דלא עשה בה מאמר ומת נכרית מיחלץ חלצה יבומי לא מיבמה דהויא צרת אחות אשה בזיקה והא דקתני מאמר לאפוקי מבית שמאי דאמרי מאמר קונה קנין גמור ואפילו חליצה נמי לא תיבעי קמ"ל דצריכה חליצה:

And this is the law even if he did not perform maamar and then died, the stranger undergoes chalitza and not yibbum, for she is the rival of his wife's sister with levirate bond. And this that the Mishna discusses maamar is to reject the position of Bet Shammai who say that maamar acquires an exemplary acquisition, and even chalitza is not required. Therefore it informs us that chalitza is required.

Mishna:

ג' אחין ב' מהן נשואין ב' אחיות ואחד נשוי נכרית ומת הנשוי נכרית וכנס אחד מבעלי אחיות את אשתו ומת הראשונה יוצאה משום אחות אשה והשניה משום צרתה עשה בה מאמר ומת נכרית חולצת ולא מתיבמת:

Three brothers, two of whom are married to two sisters, and one of them is married to a stranger, and the one who married the stranger died, and one of the husbands of the sisters married his wife {=did yibbum} and then died {such that he leaves two widows, his first wife who is one of the two sisters and the stranger who was the widow of his brother}, the first one {=the sister} goes out because of being the sister of his {the remaining brother's} wife, and the second one {the stranger} for being her rival.
If he did maamar {on the stranger} and then died {leaving his first wife who is one of the two sisters and the stranger}, the stranger undergoes chalitza and not yibbum.

ג' אחין ב' מהם נשואין שתי אחיות ואחד נשוי נכרית ומת אחד מבעלי אחיות וכנס נשוי נכרית את אשתו ומתה אשתו של שני ואחר כך מת נשוי נכרית הרי זו אסורה עולמית הואיל ונאסרה עליו שעה אחת:

Three brothers, two of whom married two sisters and one is married to a stranger, and one of the husbands of the sisters died, and the one who married the stranger married {performed yibbum} on his wife {one of the sisters}, and then the wife of the second brother {who was a sister} died {thus seemingly eliminating the prohibition of his wife's sister}, and afterwards the one who was married to the stranger died {leaving two widows, his first wife who was the stranger and the second wife who was the sister who was the widow of the first brother}, this one is prohibited to him forever since she was prohibited to him for one hour.

ג' אחין ב' מהם נשואין שתי אחיות ואחד נשוי נכרית וגירש אחד מבעלי אחיות את אשתו ומת
הנשוי נכרית וכנסה המגרש ומת זו היא שאמרו וכולן אם מתו או נתגרשו או מיאנו צרותיהן מותרות

Three brothers, two of whom married two sisters, and one of whom married a stranger, and one of the husbands of the sisters divorced his wife, and then the one who married a stranger died, and then the one who divorced his wife {who was one of the two sisters} married her {the widow in yibbum} and then died -- this is what they said "and all of them, if they died or were divorced or refused, their rivals are permitted."