כמגע עצמה מה מגע עצמה מטמא אדם לטמא בגדים אף משכבה ומושבה מטמא אדם לטמא בגדים
are like her touch itself. Just as her touch transmits impurity to a person who comes in contact with them to the extent that he transmits impurity to the garments he is wearing, so too her bed and her chair transmit impurity to a person who comes in contact with them to the extent that he transmits impurity to the garments he is wearing.
תניא כוותיה דרבא הרואה דם מטמאה מעת לעת ומה היא מטמאה משכבות ומושבות אוכלין ומשקין וכלי חרס המוקף צמיד פתיל ואינה מקולקלת למנינה ואינה מטמאה את בועלה למפרע ר' עקיבא אומר מטמאה את בועלה ואינה מונה אלא משעה שראתה
§ It is taught in a baraita in accordance with the opinion of Rava: If a woman sees menstrual blood, it renders her impure retroactively for a twenty-four-hour period. And what does she render impure during that period? Beds and chairs, food and drink, and an earthenware vessel sealed with a tightly bound cover [tzamid patil], if she moves it. But she does not disrupt her count of the periods of menstruation and ziva, i.e., she starts her cycle only from that day when she saw the blood, and she does not render impure retroactively a man who engaged in intercourse with her. Rabbi Akiva says: She does render impure a man who engaged in intercourse with her. And she counts her seven days of impurity only from the time that she saw her menstrual blood, not retroactively.
הרואה כתם מטמאה למפרע ומה היא מטמאה אוכלין ומשקין משכבות ומושבות וכלי חרס המוקף צמיד פתיל ומקולקלת למנינה ומטמאה את בועלה ואינה מונה אלא משעה שראתה
The baraita continues: With regard to a woman who sees a blood stain, it renders her impure retroactive to when the garment was last checked. And what does she render impure during that period? Food and drink, beds and chairs, and an earthenware vessel sealed with a tightly bound cover, if she moves it. And it also disrupts her count of eleven days during which emission of blood renders the woman a zava, as the time of the stain is unknown, and she renders ritually impure a man who engaged in intercourse with her. And she counts her seven days of impurity only from the time that she saw her menstrual blood, not retroactively.
וזה וזה תולין לא אוכלין ולא שורפין
The baraita further teaches: With regard to both this, one who sees menstrual blood, and that, one who sees a blood stain, if they had touched teruma, its status is suspended. It is not eaten, as impure teruma is prohibited in consumption, but it is not burned either, since it is prohibited to burn pure teruma.
ורבא אי שמיע ליה מתניתא לימא מתניתא ואי לא שמיע ליה מתניתא קל וחומר מנא ליה
The Gemara raises a difficulty: And as for Rava, why is the halakha of an earthenware vessel more obvious to him than the halakha of a bed and a chair? If he had heard this baraita, which states the halakha of an earthenware vessel, then let him say that the baraita itself is proof for his opinion with regard to a bed and a chair as well, as the baraita states both halakhot. And if he had not heard this baraita, from where did he learn his a fortiori inference, which is based on the halakha that an earthenware vessel sealed with a tightly bound cover is not spared from impurity if a menstruating woman moved it during her twenty-four-hour period of retroactive impurity?
לעולם שמיע ליה מתניתא ואי ממתניתא הוה אמינא או אדם או בגדים אבל אדם ובגדים לא משום הכי קאמר ק"ו
The Gemara answers: Actually, he did hear the baraita. But if his proof had been merely from the baraita, I would say that a different halakha applies to a bed and chair than to the earthenware vessels, as the baraita means that the bed and chair render impure a person or garments that they touch, but they do not render a person impure to the extent that he then transmits impurity to his garments. It is due to that reason that Rava says the a fortiori inference.
אמר רב הונא מעת לעת שבנדה לקדש אבל לא לתרומה אי הכי ליתני גבי מעלות כי קתני היכא דאית ליה דררא דטומאה אבל היכא דלית ליה דררא דטומאה לא קתני
§ Rav Huna says: The twenty-four-hour period of retroactive impurity of a menstruating woman applies only to sacrificial food but not to teruma. The Gemara asks: If so, let the mishna in Ḥagiga 20b teach this among the other higher levels of purity that apply to sacrificial foods but not to teruma. That mishna lists stringencies of ritual purity that are in effect with regard to sacrificial foods and not teruma. The Gemara answers: When that mishna teaches those higher levels of purity, it is referring only to types of impurity that have a connection [derara] to impurity as defined by Torah law. But it does not teach a case where there is no connection to impurity as defined by Torah law, and the retroactive impurity of a menstruating woman is by rabbinic law.
מיתיבי מה היא מטמאה אוכלין ומשקין מאי לאו בין דקדש בין דתרומה לא דקדש
The Gemara raises an objection from the aforementioned baraita that deals with the retroactive impurity of a menstruating woman: What does she render impure during that period? Food and drink. The Gemara asks: What, is it not correct to say that this is referring both to sacrificial food and to teruma? The Gemara answers: No, it is referring only to sacrificial food, not to teruma.
תא שמע רבי יהודה אומר אף בשעת עברתן מלאכול בתרומה והוינן בה מאי דהוה הוה
The Gemara suggests: Come and hear a proof from a mishna (11a): With regard to women of priestly families who must examine themselves before partaking of teruma, Rabbi Yehuda says: Even when they conclude partaking of teruma, they still need to examine themselves. And we discussed this statement of Rabbi Yehuda and asked: Why do they need to examine themselves after they finish eating teruma? What was, was; i.e., if a woman was impure when she ate the teruma, what is achieved by an examination now?
אמר רב חסדא לא נצרכה אלא לתקן שירים שבפניה
And Rav Ḥisda says in explanation: It was necessary only in order to amend the situation of the remaining teruma that is left before her, i.e., to prevent it from being rendered ritually impure. In other words, if she later experiences a flow of menstrual blood, her retroactive impurity status will not render the remaining teruma impure. This ruling apparently contradicts the opinion of Rav Huna, who said that the retroactive impurity of a menstruating woman affects only sacrificial foods, not teruma.
רב הונא מתני לישרוף שירים שבידיה שבדקה עצמה כשיעור וסת
The Gemara answers: According to Rav Huna, Rabbi Yehuda teaches that since impure teruma must be burned, she must examine herself in order to determine whether it is correct to burn the remaining teruma that was in her hands. If she examined herself immediately after eating the teruma, in the period of time needed for the onset of menstruation (see 14b), and she found that she was impure, it is assumed as a certainty that she was impure when she ate the teruma. Consequently, the remaining teruma must be burned, in accordance with the halakha of teruma that was definitely rendered impure. But in fact, Rav Huna maintains that she does not render that remaining teruma impure retroactively, in a case where she did not examine herself.
ת"ש מעשה ועשה רבי כר"א
The Gemara further suggests: Come and hear another difficulty with regard to the opinion of Rav Huna from a baraita: There was an incident in which Rabbi Yehuda HaNasi performed an action by ruling that the halakha is in accordance with the opinion of Rabbi Eliezer. Rabbi Eliezer maintains that a woman who passed three expected menstrual cycles without experiencing bleeding is presumed not to be menstruating any longer, and therefore any menstrual blood that she emits later renders her ritually impure only from then onward, but not retroactively. By contrast, the Rabbis contend that this halakha applies only to an older woman, for whom it is natural to stop menstruating, but not to a young woman, even if three typical periods have passed without bleeding.
לאחר שנזכר אמר כדי הוא ר"א לסמוך עליו
The baraita continues: After Rabbi Yehuda HaNasi remembered that Rabbi Eliezer’s colleagues disagree with Rabbi Eliezer on this matter and that he had apparently ruled incorrectly, he nevertheless said: Rabbi Eliezer is worthy [kedai] to rely upon