The Gemara answers that he could have said to you: That verse comes to teach that the belt of the High Priest is not the belt of the common priest. It is explicit in the Torah that the belt of the High Priest is made of fine blue and purple linen. On the other hand, the Torah does not state the materials used in the belt of the common priest, which was in fact linen like the rest of the garments of the common priest. And still one can say that Aaron and his sons were dressed simultaneously.

The Gemara asks: And according to the one who said that Moses dressed Aaron first and then his sons, is it not written: “And you will gird them with belts,” indicating that they were girded simultaneously? The Gemara responds that he could have said to you: That verse teaches us that the belt of the High Priest is identical to the belt of the common priest. Both of them were from fine blue and purple linen. Therefore, although the Torah distinguishes between the girding of the belts, as Moses dressed Aaron before he dressed Aaron’s sons, there was a common command to make both belts, indicating that they were made of the same material.

The Gemara asks: If they are identical, why do I need both the verse: “And he girded him with a belt,” and the verse: “And he girded them”? The Gemara explains: Learn from it that Moses dressed Aaron first and then dressed his sons. The Gemara asks: And can you find a situation where Moses could have girded Aaron and his sons simultaneously? The Gemara explains: It is necessary only to state that Moses girded Aaron first and then proceeded to gird his sons in order of their significance. After girding Aaron he did not dress Aaron in any other garments before girding his sons.

§ After a long digression in which many peripheral issues were addressed, the Gemara returns to interpreting the mishna. It was taught in the mishna: The Sages would remove the High Priest from his house to the Chamber of Parhedrin. The Gemara asks: Why do the Sages remove him? The Gemara asks in astonishment: Why do the Sages remove him? It is as we stated above: Whether it is according to Rabbi Yoḥanan, as per his opinion: Sequestering of the High Priest is derived from the sequestering prior to the inauguration; or whether it is according to Reish Lakish, as per his opinion: Sequestering of the High Priest is derived from sequestering at Sinai, the answer is clear. What is the point of the Gemara’s question?

The Gemara explains: This is what the Gemara is saying. Why did he withdraw from his house, i.e., his wife? The Gemara explained why he must be removed to a special location; but why doesn’t his wife join him? It was taught in a baraita: Rabbi Yehuda ben Beteira says: It is due to the concern lest his wife be found to be in a situation of uncertainty as to whether or not she has the halakhic status of a menstruating woman, and he will have relations with her and become impure.

The Gemara asks in astonishment: Is that to say that we are dealing with wicked people? Will the High Priest, aware of the uncertain status of his wife, have relations with her? Rather, rephrase the statement: It is due to the concern lest he have relations with his wife and then she be found to be in a situation of uncertainty as to whether or not she has the halakhic status of a menstruating woman. In a case where blood is found on the sheets after the couple engaged in relations, and there is uncertainty as to whether or not the High Priest had relations with his wife while she had the halakhic status of a menstruating woman, the status of the High Priest is one of uncertain impurity.

The Sages stated the following assumption before Rav Ḥisda: In accordance with whose opinion is that a reason for concern? It is in accordance with the opinion of Rabbi Akiva, who said: A menstruating woman who found blood on the sheets within twenty-fours after having relations, creating uncertainty with regard to her status when she engaged in relations, renders the man who had with relations with her retroactively impure. As, if it were in accordance with the opinion of the Rabbis, it is difficult: Didn’t they say that a woman with regard to whom there is uncertainty as to whether or not she has the halakhic status of a menstruating woman does not render the man who had with relations with her retroactively impure. Therefore, the High Priest need not leave his wife during the week prior to Yom Kippur.

Rav Ḥisda said to the Sages: Even if you say that the mishna is in accordance with the opinion of the Rabbis, the Rabbis disagree with Rabbi Akiva with regard to retroactive impurity only in a case where blood was discovered on the sheets long afterward, after there was time for the woman to leave the bed and bathe and only then discover the blood. Due to the time that elapsed, the Rabbis hold that there is no way to prove a connection between when the woman menstruated and when they engaged in relations. However, if the blood was found merely afterward, the Rabbis concede to Rabbi Akiva that she renders the man retroactively impure.

Rabbi Zeira said: Learn from it that one who is impure because he had relations with a menstruating woman is unlike a menstruating woman in terms of the time of immersion. Unlike the woman, who immerses after nightfall following the seventh day after her menstruation ceased, such a man may immerse on the seventh day and need not wait for nightfall. Therefore, if a High Priest has relations with his wife just before he is sequestered and there is uncertainty as to whether she has the halakhic status of a menstruating woman, the seventh day of his impurity occurs on Yom Kippur eve. He immerses himself that day and completes the purification process at nightfall. This allows him to enter the Temple to perform the Yom Kippur service.

As, if you say that one who is impure because he had relations with a menstruating woman is like a menstruating woman in terms of the time of immersion, when does he immerse? He may immerse only at night after seven complete days. Since that night is Yom Kippur, how can he perform the Yom Kippur service the next day? Isn’t he required to wait for sunset following his immersion to complete the purification process? Until then his status is that of one who immersed that day, who may not serve in the Temple until the nightfall following his immersion. Rather, must one not conclude from it that one who is impure because he had relations with a menstruating woman is unlike a menstruating woman in terms of the time of immersion? He immerses on the seventh day, Yom Kippur eve, and at nightfall he may serve in the Temple.

Rav Shimi from Neharde’a says: Even if you say that one who is impure because he had relations with a menstruating woman is like a menstruating woman with regard to the time of immersion, the High Priest is not removed from his house at night. Rather, we sequester him one hour just before sunset on the eighth day prior to Yom Kippur, slightly before the start of the seven-day period, leaving seven full days to count prior to Yom Kippur. Although he is removed from his house more than seven days prior to Yom Kippur, that slight addition is not sufficient to have the period considered eight days.

The Gemara raises an objection to the opinion that one who is impure because he had relations with a menstruating woman immerses at night: With regard to all those obligated in immersions, their immersion is during the day. The exceptions are a menstruating woman and a woman after childbirth, whose immersion is at night. It can be learned by inference: With regard to a menstruating woman, yes, she immerses at night; with regard to one who is impure because he had relations with a menstruating woman, no, he does not immerse at night.

The Gemara rejects that proof because the term menstruating woman in that baraita includes the woman and everyone whose inclusion in the impurity is derived from her status. The understanding is that a man who has relations with a menstruating woman assumes her impurity, and therefore his immersion would be identical to hers.

The Gemara raises another objection: The halakhic status of one who is ritually impure due to a seminal emission is like that of one who came into contact with a creeping animal, whereas the legal status of one who is ritually impure because he had relations with a menstruating woman is like that of one who became impure with ritual impurity imparted by a corpse. The Gemara asks: What, does the baraita not mean that one who had relations with a menstruating woman is like one impure with impurity imparted by a corpse in terms of immersion, which he may perform during the day? The Gemara rejects that conclusion. No, the baraita is merely comparing the duration of their impurity. One who experiences a seminal emission is impure for one day, like one who came into contact with a creeping animal; one who has relations with a menstruating woman is impure for seven days, like one impure with impurity imparted by a corpse.

The Gemara wonders: For what purpose would the baraita come to teach the duration of their impurity? The Torah explicitly writes the durations of their impurity. This, one impure with impurity imparted by a corpse, has impurity of seven days written in his regard; and similarly, that, one who is impure because he had relations with a menstruating woman, has impurity of seven days written in his regard. There is no need for the baraita to derive a matter explicitly written in the Torah from another matter explicitly written in the Torah.