Study Niddah folio 64A with parallel Hebrew-English text, traditional commentary, and modern study tools. Free access to Babylonian Talmud online.
Talmud: It was stated: If a woman saw menstrual blood on the 15th of this month, and on the 16th of the month after that, and on the 17th of the month after that, Rav says: She has thereby determined her menstrual cycle by skipping, i.e., as a month and a day. And Shmuel says: Her menstrual cycl
The Talmud suggests: Shall we say that Rav and Shmuel disagree with regard to the issue that is the subject of the dispute between R' Yehuda HaNasi and Rabban Shimon ben Gamliel? As it is taught in a baraita: If a woman was married to her first husband and he died, and was then married to a second
The Talmud rejects this suggestion: No, everyone agrees that the halakha is in accordance with the opinion of Rabban Shimon ben Gamliel, that a presumption is established only after 3 times, and here they disagree with regard to this matter: Rav holds that when she experienced bleeding on the 15th
Shmuel raised an objection to the opinion of Rav from a baraita: If a woman was accustomed to see a flow of blood on the 15th day of the month, and deviated and instead experienced bleeding on the 16th day of the month, on both this day, the 15th, and that day, the 16th, it is prohibited for her to
If she subsequently deviated and experienced bleeding on the 18th day of the following month, all the days are permitted. The 15th is permitted because she has now experienced bleeding 3 times on a different day, while the other days are permitted because she experienced bleeding only once on each