If a woman sat and did not examine herself every morning and evening to determine whether she emitted blood and is impure, it makes no difference whether she failed to examine herself unwittingly or due to circumstances beyond her control, or even if she acted intentionally and did not examine herself; she remains ritually pure. She is rendered impure only if she examined herself and was found to have emitted blood.

By contrast, if the time of her menstrual cycle arrived, when she is required to examine herself, and she did not examine herself, that woman is ritually impure, as it is typical for a woman to discharge blood at that time. Rabbi Meir says: If a woman was in hiding from danger, and the time of her menstrual cycle arrived and she did not examine herself on that day, that woman is pure, because fear drives away blood. There is therefore no concern that she might have emitted blood.

But with regard to the seven clean days of the zav and the zava, and with regard to a woman who observes a clean day for a day she experiences a discharge during her days of ziva, if she fails to examine herself on those days, these women have a presumptive status of ritual impurity, as they already experienced a discharge.

GEMARA: The mishna teaches that throughout the eleven days of ziva that follow the seven days of menstruation, a woman has the presumptive status of ritual purity. The Gemara asks: With regard to what halakha is this stated? Rav Yehuda says: This serves to say that she does not require an examination during these days. The Gemara objects: But from the fact that the latter clause teaches: If she sat and did not examine herself she remains ritually pure, it can be inferred that she requires examination ab initio.

The Gemara explains: In the latter clause we arrive at the case of a woman who is in the days of menstruation, not in the days of ziva. And this is what the mishna is saying: For all the eleven days of ziva that follow the days of menstruation, a woman has the presumptive status of ritual purity and she does not require examination. But during the days of her menstruation she requires examination. Nevertheless, if she sat and did not examine herself, whether unwittingly or due to circumstances beyond her control, or even if she acted intentionally and did not examine herself, she remains ritually pure.

Rav Ḥisda said a different answer: The first clause of the mishna is necessary only for the opinion of Rabbi Meir, who said: With regard to a woman who does not have a fixed menstrual cycle, she is forbidden to engage in intercourse, lest she emit blood during intercourse. The mishna is teaching that this statement applies only during the days of her menstruation, but during the days of her ziva even Rabbi Meir concedes that she stands in her presumptive status of purity and may engage in intercourse with her husband.

The Gemara asks: If so, that even according to Rabbi Meir there are days in which a woman who does not have a fixed menstrual cycle is permitted to engage in sexual intercourse with her husband, why did Rabbi Meir say that her husband must divorce her and he may never take her back, even if she eventually develops a fixed menstrual cycle? Let them engage in intercourse during the eleven days of ziva. The Gemara answers: He must divorce her lest the matter lead to failure during the days of menstruation, i.e., in case they come to engage in intercourse during the days of menstruation, when she might experience regular menstrual bleeding.

The Gemara objects: But from the fact that the latter clause teaches: If the time of her menstrual cycle arrived and she did not examine herself, that woman is ritually impure, it can be inferred that we are dealing with a woman who has a fixed menstrual cycle. The Gemara explains: The mishna is incomplete and this is what it is teaching: For all the eleven days of ziva that follow the days of menstruation, a woman has the presumptive status of ritual purity and she is permitted to her husband, but during the days of menstruation she is prohibited to her husband.

In what case is this statement said? In the case of a woman who does not have a fixed menstrual cycle, where there is a concern she might experience bleeding during any of the days of menstruation. But in the case of a woman who has a fixed menstrual cycle, she is permitted to engage in sexual intercourse with her husband, and she requires examination. Nevertheless, if she sat and did not examine herself, whether unwittingly or due to circumstances beyond her control, or even if she acted intentionally and did not examine herself, she remains ritually pure. If the time of her menstrual cycle arrived and she did not examine herself, she is impure.

The Gemara objects: But from the fact that the last clause is in accordance with the opinion of Rabbi Meir, it can be inferred that the first clause is not in accordance with the opinion of Rabbi Meir. The Gemara explains that the entire mishna is in accordance with the opinion of Rabbi Meir, and this is what it is saying: If she was not in hiding and the time of her menstrual cycle arrived and she did not examine herself, she is impure, as Rabbi Meir says: If a woman was in hiding and the time of her menstrual cycle arrived and she did not examine herself, she is pure, as fear drives away blood.

Rava says a different explanation of the first clause of the mishna: The mishna is coming to say that if a woman experiences bleeding during the eleven days of ziva, as she previously had the presumptive status of purity she does not impart impurity retroactively for a twenty-four-hour period to any ritually pure items she touched. It is assumed that she did not emit any blood before this emission.

The Gemara raises an objection from a baraita: With regard to a menstruating woman, and a zava, and a woman who observes a day for a day, and a woman who gave birth, they all impart impurity retroactively for a twenty-four-hour period. A woman who observes a day for a day is one who experiences bleeding for one or two days during her days of ziva, and the baraita teaches that even such a woman imparts impurity retroactively for a twenty-four-hour period. If so, this is a conclusive refutation of Rava’s explanation.

Rav Huna bar Ḥiyya says another explanation of the first clause of the mishna in the name of Shmuel: The mishna is coming to say that a woman does not fix a menstrual cycle for herself during the days of her ziva. In other words, a sighting during these days does not combine with sightings during the previous two periods of ziva to establish a fixed menstrual cycle. The Gemara relates that this statement was recited before Rav Yosef, who said: I did not hear this halakha from Shmuel.

Abaye said to him: But you yourself told us this halakha, and it was with regard to that mishna you told it to us, as we learned in a mishna (63b): If the woman was accustomed to see an emission of blood on the fifteenth day, so that this was her fixed menstrual cycle, and she deviated from her cycle to see an emission on the twentieth day, then on both this day, the fifteenth, and that day, the twentieth, it is prohibited for her to engage in sexual intercourse due to the concern that she might have an emission on either day. If she deviated from her cycle twice, to see an emission on the twentieth day, then on both this day and that day it is prohibited for her to engage in intercourse. If she deviates a third time to see on the twentieth she has established for herself a new fixed menstrual cycle.

Abaye continues: And you said to us with regard to this mishna that Rav Yehuda said that Shmuel said: They taught this halakha only with regard to a woman who normally experiences bleeding fifteen days from her immersion, which are twenty-two days from her sighting of menstrual blood. This means that there, she stands in her days of menstruation. But if she normally experiences bleeding fifteen days from her sighting of menstrual blood, so that she stands in her days of ziva, she has not fixed a menstrual cycle, and the previous cycle is uprooted even if she deviates from it only once.

§ With regard to the ruling that a woman’s menstrual cycle cannot be fixed during her days of ziva, Rav Pappa said: I said this halakha before Rav Yehuda of Diskarta, and I asked him for a clarification of the following matter: Granted, she does not fix a menstrual cycle during the days of ziva, and there is no need for three deviations to uproot her cycle; rather, it is uprooted by even one deviation. But what is the halakha with regard to whether we should be concerned that she might experience bleeding? In other words, if she normally experiences bleeding on a particular day during her days of ziva, must she avoid engaging in sexual intercourse with her husband on that day out of concern that she might emit blood?

Rav Yehuda of Diskarta was silent and did not say anything to Rav Pappa. Therefore, Rav Pappa said: Let us see and try to resolve this ourselves. The mishna cited above states: If the woman was accustomed to see an emission of blood on the fifteenth day, and she deviated from her cycle to see an emission on the twentieth day, then on both this day and that day it is prohibited for her to engage in sexual intercourse.