It is prohibited for camel riders to partake of teruma, due to the concern for a seminal emission that might result from the friction. The Gemara notes: This opinion of Abaye is also taught in a baraita: Camel riders are all wicked, as they are suspected of emitting semen for naught. Sailors are all righteous, because they are in a constant state of danger at sea, and therefore their hearts are always turned to God in prayer.

The baraita continues: As for donkey drivers, some of them are wicked while some of them are righteous. With regard to the difference between wicked and righteous donkey drivers, there are those who say that this donkey driver is righteous, as his donkey is saddled, and therefore his penis does not rub against it, whereas that donkey driver is wicked, as his donkey is not saddled, which can cause a seminal emission. And there are those who say: This donkey driver is wicked, as he spreads [demittartein] his thighs on either side of the donkey, whereas that donkey driver is righteous as he does not spread his thighs in this manner, but rides with both legs on one side of the donkey, so that his penis does not rub against the donkey.

The Gemara further discusses actions that are apt to lead to a seminal emission. Rabbi Yehoshua ben Levi would curse one who sleeps lying on his back [aparkeid], as this might lead to a seminal emission. The Gemara asks: Is that so? But doesn’t Rav Yosef say: One who is lying on his back may not recite Shema? From this it may be inferred that it is only Shema that one may not recite in this position, but to sleep lying in that position is permitted.

The Gemara answers: With regard to the prohibition against sleeping while lying on one’s back, when one leans slightly to the side it is permitted. But with regard to reciting Shema while lying face upward, even when one leans slightly to the side it is prohibited. The Gemara asks: But wouldn’t Rabbi Yoḥanan lie on his back leaning slightly to the side and recite Shema in this manner? The Gemara answers: The halakha in the case of Rabbi Yoḥanan is different, as he was corpulent, and consequently he could lean only slightly.

MISHNA: It is the custom of Jewish women that they engage in intercourse with their husbands while using two examination cloths, one for the husband, to see if there is any of the wife’s blood on him after intercourse, and one for her, to ascertain after intercourse whether her menstrual flow has begun. And the modest women prepare a third examination cloth, to examine themselves and prepare the pubic area for intercourse.

If blood was found on his cloth, the woman and her husband are both ritually impure for seven days, in accordance with the halakha of a menstruating woman and of one who engages in intercourse with a menstruating woman, and are each liable to bring a sin offering for unwittingly performing an action punishable with excision from the World-to-Come [karet]. If blood was found on her cloth immediately [otyom] after intercourse, the woman and her husband are likewise ritually impure for seven days and are each liable to bring a sin offering. If blood was found on her cloth after time passed, they are both ritually impure due to uncertainty, as it is possible that the blood appeared only after intercourse, and they are exempt from bringing the sin offering.

What is considered as being: After time passed? It is a period of time equivalent to the time needed for her to descend from the bed and rinse her face, a euphemism for her pubic area. And afterward, she retroactively transmits impurity to all ritually pure items with which she came into contact for the preceding twenty-four-hour period, by rabbinic law, but she does not transmit seven-day impurity to the man with whom she engaged in intercourse. He is impure with this impurity by rabbinic law only until the evening, like one who came in contact with a menstruating woman. Rabbi Akiva says: In the case where blood was found on her cloth after time passed, she even transmits seven-day impurity by rabbinic law to the man with whom she engaged in intercourse.

The mishna concludes: The Rabbis concede to Rabbi Akiva in the case of a woman who sees a blood stain and then engages in intercourse, that she transmits seven-day impurity to the man with whom she engaged in intercourse, although this impurity also applies by rabbinic law.

GEMARA: The mishna states that if blood is found on the husband’s cloth after intercourse the husband and wife are both definitely impure. The Gemara asks: But let us be concerned that perhaps it is the blood of a louse, as it is possible that there was a louse in the woman’s pubic area that was squashed during intercourse, and its blood was found on the husband’s penis. Accordingly, it should be uncertain if they are impure. Rabbi Zeira says: There is no concern for this possibility, as that place, a woman’s genitals, is considered examined [baduk] with regard to the appearance of a louse, i.e., it is clear that no louse was there. And some say a different version of Rabbi Zeira’s statement: That place is too narrow [daḥuk] for a louse to enter, and therefore this is not a concern.

The Gemara asks: What is the practical difference between these two versions of Rabbi Zeira’s statement? The Gemara answers: There is a practical difference between them in a case where a squashed louse was found on the husband’s cloth, near the blood: According to this version, which states that a woman’s genitals are considered examined with regard to a louse, this louse certainly came from elsewhere, as a louse is never found in her pubic area, so the blood on the cloth is clearly from the woman, and therefore the couple is ritually impure. By contrast, according to that version, which states that the place is too narrow for a louse to enter, one can say that although it is generally too narrow, in this case one did enter and the man’s organ squashed it during intercourse, and therefore their impurity is uncertain.

It was stated: If the woman examined herself with a cloth that was examined by her before she used it and found free of blood, and after the examination she pressed it against her thigh, and did not look at the cloth, and on the following day she found blood on her thigh, Rav says: In such a case she is definitely impure as a menstruating woman. Since it is known that the cloth was clear of blood before the examination, the blood on her thigh must be from her examination, and it must have passed onto her thigh after the cloth was pressed there. Rav Shimi bar Ḥiyya said to Rav: But didn’t you say to us with regard to this case that she needs to be concerned for ritual impurity, which indicates that her impurity is uncertain?

In this regard it was also stated that Shmuel says: She is definitely impure as a menstruating woman. And they likewise rule as a practical halakha in the study hall that this woman is definitely impure as a menstruating woman.

With regard to a similar case, it was stated: If a woman examined herself with a cloth that was not examined by her before its use, and she then placed it in a box without looking at it, and on the following day she found blood on this cloth, the question is whether the blood was on the cloth before the examination and the woman is consequently not impure, or whether the blood is from the examination, and she is impure. Rav Yosef says: All the days of Rabbi Ḥiyya he would deem such a woman impure, but in his old age he would deem her pure.

A dilemma was raised before the Sages with regard to this statement of Rav Yosef: With regard to what type of impurity status is he speaking? Does he mean that all his days Rabbi Ḥiyya would deem the woman definitely impure as a menstruating woman, and therefore any teruma with which she came into contact required burning; and in his old age he would deem her pure from the definite impurity status of a menstruating woman, but would deem her impure as a woman who discovered a stain, which is an uncertain source of impurity? If so, according to his ruling from his old age any teruma she touches is not burned but may not be eaten.

Or perhaps does Rav Yosef mean that all his days Rabbi Ḥiyya would deem the woman impure as a matter of uncertainty due to the stain, and in his old age he would deem her pure from any type of impurity status?

The Gemara suggests: Come and hear a resolution for this dilemma, as it is taught in a baraita: If a woman examined herself with a cloth that was not examined by her before its use, and she placed it in a box, and on the following day she found blood on this cloth, Rabbi Yehuda HaNasi says: She is definitely impure as a menstruating woman, and Rabbi Ḥiyya says: She is impure as a matter of uncertainty due to the stain.