Yevamot

AND THE LAW IS THE SAME WHETHER THERE IS ONE SISTER-IN-LAW TO ONE LEVIR OR TWO SISTERS-IN-LAW TO ONE LEVIR. HOW?  — IF THE LEVIR ADDRESSED A MA'AMAR TO THE ONE  AND A MA'AMAR TO THE OTHER,  TWO LETTERS OF DIVORCE  AND ONE HALIZAH  ARE REQUIRED.  IF HE ADDRESSED A MA'AMAR TO ONE AND GAVE A LETTER OF DIVORCE TO THE OTHER, [THE ONE] REQUIRES A LETTER OF DIVORCE  AND [THE OTHER MUST PERFORM] THE HALIZAH.  IF HE ADDRESSED A MA'AMAR TO ONE AND COHABITED WITH THE OTHER, BOTH REQUIRE LETTERS OF DIVORCE  AND [ONE MUST PERFORM] THE HALIZAH.  IF HE ADDRESSED A MA'AMAR TO ONE AND SUBMITTED TO HALIZAH FROM THE OTHER, IT IS NECESSARY FOR THE FIRST TO OBTAIN A LETTER OF DIVORCE. IF THE LEVIR GAVE A LETTER OF DIVORCE TO ONE AS WELL AS TO THE OTHER, HALIZAH IS NECESSARY FOR BOTH.  IF HE GAVE A LETTER OF DIVORCE TO ONE AND COHABITED WITH THE OTHER, [THE SECOND] REQUIRES A LETTER OF DIVORCE  AND MUST ALSO PERFORM THE HALIZAH.  [IF HE GAVE] A LETTER OF DIVORCE TO ONE AND ADDRESSED A MA'AMAR TO THE OTHER, [THE SECOND] REQUIRES A LETTER OF DIVORCE AND [ONE OF THEM MUST PERFORM] THE HALIZAH. [IF HE GAVE] A LETTER OF DIVORCE TO ONE AND SUBMITTED TO HALIZAH FROM THE OTHER, THERE IS NO VALIDITY IN ANY ACT THAT FOLLOWS THE HALIZAH. IF THE LEVIR SUBMITTED TO HALIZAH FROM THE ONE AND FROM THE OTHER, OR SUBMITTED TO HALIZAH [FROM ONE] AND ADDRESSED [TO THE OTHER] A MA'AMAR, GAVE HER A LETTER OF DIVORCE, OR COHABITED WITH HER; OR IF HE COHABITED WITH THE ONE AND WITH THE OTHER, OR COHABITED [WITH THE ONE] AND ADDRESSED [TO THE OTHER] A MA'AMAR, GAVE HER A LETTER OF DIVORCE, OR SUBMITTED TO HER HALIZAH, NO ACT IS VALID AFTER THE HALIZAH.  [THERE IS NO DIFFERENCE IN THE LAW] WHETHER THERE WAS ONE LEVIR TO TWO SISTERS-IN-LAW OR TWO LEVIRS TO ONE SISTER-IN-LAW. [IF THE LEVIR]  SUBMITTED TO HALIZAH AND THEN ADDRESSED TO HER  A MA'AMAR, GAVE HER A LETTER OF DIVORCE, OR COHABITED WITH HER; OR IF HE COHABITED WITH HER AND THEN ADDRESSED TO HER A MA'AMAR, GAVE HER A LETTER OF DIVORCE, OR SUBMITTED TO HALIZAH, NO ACT IS VALID AFTER THE HALIZAH, WHETHER [IT WAS PERFORMED] IN THE BEGINNING, IN THE MIDDLE,  OR AT THE END.  IN THE CASE OF COHABITATION, IF IT TOOK PLACE FIRST NO ACT THAT FOLLOWS IT HAS ANY VALIDITY; IF IT OCCURRED, HOWEVER, IN THE MIDDLE  OR AT THE END  SOMETHING VALID  STILL REMAINS.  R. NEHEMIAH SAID: WITH COHABITATION AS WITH HALIZAH, WHETHER IT TOOK PLACE IN THE BEGINNING, IN THE MIDDLE, OR AT THE END, THERE IS NO VALIDITY IN ANY ACT THAT FOLLOWS IT. GEMARA. Their difference  concerns only a letter of divorce after another letter of divorce and a ma'amar after another ma'amar, but one letter of divorce to one sister-in-law or one ma'amar to one sister-in-law is valid. Why did the Rabbis say that a letter of divorce to one sister-in-law is valid?  — Because it is also valid elsewhere.  For should you suggest that it is not valid,  it might be argued that since a letter of divorce serves to release a woman and halizah serves to release a woman, as the letter of divorce is of no effect,  so is the halizah also of no effect, and thus one would come to consummate marriage after halizah. And why did the Rabbis say that a ma'amar with one sister-in-law is valid?  — Because it is valid elsewhere.  For should you say that it is not valid,  it might be argued that since a ma'amar serves the purpose of acquisition  and cohabitation serves the purpose of acquisition,  as a ma'amar is of no effect,  so is cohabitation also of no effect  and one would thus consummate marriage  after an act of cohabitation. And why did the Rabbis say that after an invalid cohabitation something  lingers?  — It might be replied that if it is a cohabitation  after a letter of divorce,  a preventive measure was made  against cohabitation after halizah;  and if it is a cohabitation  after a ma'amar  a preventive measure had to be made  against cohabitation after cohabitation. And why did the Rabbis say that after the invalid halizah  nothing lingers?  — It may be replied: What kind of preventive measure could have been enacted! Should halizah after a letter of divorce be forbidden as a preventive measure against halizah after halizah?  Under such circumstances, surely, halizah might well be indefinitely continued!  And should halizah after a ma'amar be forbidden as a preventive measure against halizah after cohabitation?  Surely [it may be replied] is not in the case of halizah after a ma'amar, a letter of divorce required in respect of one's ma'amar? So also in the case of halizah after cohabitation, a letter of divorce is required in respect of one's cohabitation. Raba said: