Rather, it is sufficient if you come back again tomorrow and speak with me then about this matter. And Rav Naḥman bar Yitzḥak knew what she was saying to him. She was alluding to the fact that she had not washed her hair while it was still daylight, and therefore she could not immerse that evening. Rav Naḥman bar Yitzḥak said to her: Are you lacking kettles [dudei] to heat water to wash your hair? Are you lacking buckets [tashtekei] to bring the water to wash your hair? Are you lacking servants, who can help you prepare to wash your hair? It can be inferred from this story that Rav Naḥman bar Yitzḥak holds that it is permitted for a woman to wash her hair and immerse on the same night.

§ Rava taught: A woman may wash her hair on the eve of Shabbat and immerse at the conclusion of Shabbat. Rav Pappa said to Rava: But didn’t Ravin send the following halakha in his letter: A woman may not wash her hair on the eve of Shabbat and immerse at the conclusion of Shabbat? Instead, she should wash her hair after the conclusion of Shabbat immediately before she immerses.

And furthermore, you should be astounded with yourself: How did the Sages deem it permitted for a woman on a weekday to wash her hair during the day and immerse at night? Don’t we require that her immersion must be immediately after washing her hair? And if she washes her hair during the day, this requirement will not be fulfilled. The Sages reluctantly permitted a woman to wash her hair during the day, and they permitted this only due to the concern that she might not wash her hair properly if she would wait until night. Consequently, with regard to an immersion on the conclusion of Shabbat, she should avoid washing her hair a day or more in advance.

As a result of Rav Pappa’s comments, Rava then appointed an interpreter before him to publicize his retraction, and he taught: The statement I said to you was a mistake of mine. But in fact this is what the Sages said in the name of Rabbi Yoḥanan: A woman may not wash her hair on the eve of Shabbat and immerse after the conclusion of Shabbat. And furthermore you should be astounded with yourself. How can a woman wash her hair during the day and immerse at night? Don’t we require: Her immersion must be immediately after washing her hair? And if she washes her hair on the eve of Shabbat, this principle will not be fulfilled.

The Gemara concludes: And the halakha is that a woman may wash her hair during the day and immerse at night. And the halakha is that a woman may wash her hair only at night. The Gemara comments: This is difficult, as one halakha contradicts the other halakha.

The Gemara answers: It is not difficult. This ruling that she may wash her hair during the day is referring to a case where it is possible, e.g., when she immerses on a weeknight and can wash her hair shortly beforehand during the daytime. That ruling that she is permitted to wash her hair only at night is referring to a case where it is not possible, e.g., when her time for immersion is after the conclusion of Shabbat. Since she may not wash her hair on the eve of Shabbat for an immersion after the conclusion of Shabbat, she must wash her hair at night, after Shabbat has ended, immediately before she immerses.

MISHNA: In the case of a menstruating woman who examined herself on the seventh day of menstruation in the morning and found that she is ritually pure and eligible to immerse in a ritual bath that evening, but during twilight of the seventh day she did not perform an examination that marks the transition between the days when she has a flow of blood and the days when she no longer has a flow of blood but immersed despite not having performed the examination, and after several days she examined herself and found that she is ritually impure, the presumptive status of that woman is one of ritual purity from the time of her immersion until her examination, and all ritually pure items that she handled in the interim remain pure.

If she examined herself on the seventh day of menstruation in the morning and found that she is ritually impure, i.e., her menstrual flow continued, and during twilight of the seventh day she did not perform an examination to confirm the transition from ritual impurity to ritual purity but immersed nonetheless, and after several days she examined herself and found that she is ritually pure, the presumptive status of that woman is one of ritual impurity from the time of her immersion until her examination, and all ritually pure items that she handled in the interim are impure. Since she found blood during her last examination in her days of menstruation, the concern is that the flow of blood continued during the days that followed, and therefore her immersion on the eve of the eighth day was ineffective.

In a case where there was no blood found during the examination on the seventh morning and she did not examine herself during twilight, and several days later she discovered blood, where the mishna says that a woman’s presumptive status is one of ritual purity, that is the halakha only for the days following immersion. But she transmits ritual impurity to the ritually pure items that she handled before the examination in which she found blood for a twenty-four-hour period and from examination to examination, in accordance with the halakha of a woman who experiences bleeding (see 2a). And if she has a fixed menstrual cycle, on the day that she examined herself and found blood, her time is sufficient, i.e., it is assumed that the bleeding began then, and she does not transmit impurity retroactively.

And Rabbi Yehuda says: With regard to any woman who did not perform the examination marking her transition from ritual impurity to ritual purity on the seventh day from minḥa time onward, even if she performed an examination and found no blood that morning, the presumptive status of that woman is one of ritual impurity. And the Rabbis say: Even if on the second day of her menstruation she performed the examination and found that she is ritually pure, and she did not perform the examination marking her transition from ritual impurity to ritual purity on the seventh day during twilight, and after several days she examined herself and found that she is ritually impure, the presumptive status of that woman is one of ritual purity from the time of her immersion until her examination.

GEMARA: The Gemara cites a dispute between amora’im with regard to a case where a woman did not perform an examination indicating her transition from ritual impurity to ritual purity, and three days passed in which it is possible that she received the status of a zava, and then she found that she was ritually impure. It was stated that Rav says: This woman is a definite greater zava. And Levi says: She is an uncertain greater zava.

The Gemara asks: To which clause of the mishna does this dispute apply? If we say that Rav and Levi are referring to the first clause, i.e., a woman who examined herself on the morning of the seventh day and found herself to be ritually pure, but she did not examine herself at twilight, and several days later she examined herself and found herself to be impure, this cannot be correct, as the mishna teaches: The presumptive status of that woman is one of ritual purity. She is not a zava at all.

Rather, say that they are referring to the latter clause of the mishna, when she examined herself on the morning of the seventh day and found herself to be ritually impure. If so, granted Levi’s opinion is reasonable, as we say that this woman is an uncertain greater zava. But how can one explain Rav’s opinion that she is even a definite greater zava? After all, she examined herself and found that she is ritually pure. If so, how can she be a definite zava?

Rather, when the dispute of Rav and Levi was stated, it was stated as a distinct halakha unrelated to the mishna, as follows: With regard to a menstruating woman who examined herself on the seventh day in the morning and found that she was ritually impure, and at twilight of the seventh day she did not perform an examination to confirm her transition from ritual impurity to ritual purity, and after several days she examined herself and found that she is ritually impure, Rav says: This woman is a definite greater zava. And Levi says: She is an uncertain greater zava.

The Gemara explains their opinions. Rav says: This woman is a definite greater zava, since from the outset she found herself to be ritually impure, and now she found herself to also be ritually impure. Consequently, she is definitely impure. And Levi says: This woman is an uncertain greater zava, as one can say that perhaps she stopped experiencing bleeding in between the morning of her seventh day of menstruation when she first found herself to be impure and several days later, on the second occasion that she found herself to be impure.