(Mishnah - Shamai): (Once blood leaves a woman's Makor, i.e. her source of menstrual blood, and enters the Beis ha'Chitzon (outside the Makor, but still inside her body), she is Teme'ah.) If any woman sees that she became a Nidah (through a Bedikah, or blood left her body), Dayah Shaitah. (She is Teme'ah from now and onwards, but not retroactively);

Hillel says, she is retroactively Teme'ah from her last Bedikah (when she checked her Beis ha'Chitzon and did not find blood) even if it was many days [earlier].

Chachamim say, it is not like [Shamai] and not like [Hillel]. Rather, 24 hours reduce [retroactive Tum'ah] from the time of her last Bedikah (if it was more than 24 hours ago), and her last Bedikah (if it was in the last 24 hours) reduces from 24 hours.

Any woman who has a Veses (regular period when she becomes a Nidah), Dayah Shaitah.

If (Mishnah): A woman who has relations with Edim (she checks herself before and after relations), this is like a Bedikah. It reduces [retroactive Tum'ah] from 24 hours and from the last Bedikah.

(Gemara): What is Dayah Shaitah? She is not Metamei Taharos retroactively.

Chachamim say, it is not like this one and not like this one. It is not like Shamai, who did not give a fence for his words, and not like Hillel, who was too extreme;

Rather, 24 hours reduce from the time of her last Bedikah, and her last Bedikah reduces from 24 hours.

How do 24 hours reduce from the time of her last Bedikah? If she checked herself on Monday and saw [blood] on Thursday, [Taharos that she touched] are Tamei only from 24 hours ago, on Wednesday;

How does her last Bedikah reduce from 24 hours? If she checked herself in the morning and saw in the afternoon, Taharos that she touched] are Tamei only from the morning.

(Mishnah): If a Sheretz was found in a Mavuy, [all Taharos that were made there] are retroactively Teme'im.

Question (R. Ami): Is our Mishnah unlike Shamai?

Answer #1 (R. Yosi): Yes, it is unlike Shamai.

Objection: [If you compare a woman to a Mavuy,] it is not even like Hillel! Doesn't Hillel agree about a Mavuy that is swept or a stream of rain passes through, that [retroactively] it is Tahor?! (A Sheretz would have been swept or washed away.)

Answer #2: Shamai says, since, a woman regularly urinates, we considered her like a Mavuy that is swept or a stream of rain passes through, that it is Tahor [retroactively].

[Our Mishnah says that a Bedikah limits retroactive Tum'ah] only when she checked and found it dry. If she checked and found [an appearance that is] Tahor, R. Ami says in the name of R. Ba in the name of Rav Yehudah, if she checked and found that she is Tahor, she is forbidden until her Mayan (source of blood) dries up [lest Tamei appearances come out].

Rav Tuvi said in the name of R. Avahu, she is forbidden to her husband for 24 hours.

(R. Yakov bar Acha): When I came here [to Eretz Yisrael], I heard from all the Rabanan that she is permitted to her husband immediately.

Suggestion: The one who says that she is permitted to her husband [immediately, a Tahor appearance] is like a Bedikah to reduce from 24 hours. The one who forbids to her husband holds that it is not like a Bedikah to reduce from 24 hours.

Rejection: Even the one who forbids to her husband holds that it is like a Bedikah to reduce from 24 hours. Why is she forbidden to her husband? Since she regularly sees Tahor blood, she regularly (i.e. we are concerned lest she) see Tamei blood.

Question: If she checked and found a Safek, obviously it is not like a Bedikah to reduce from 24 hours. Is it Metamei [retroactively] due to Safek?

Answer: We learn from the following [Tosefta]. If a Tumtum or Androginus saw [blood], Dayah Shaitah.

Question: How do we learn from this?

Answer (R. Yosi): A Tumtum or Androginus is a Safek (perhaps he is a male, and his blood is Tahor), and 24 hours is a Safek. We are not concerned for a Safek about a Safek. Also here, her sighting is (i.e. she checked and found) a Safek, and 24 hours is a Safek. We are not concerned for a Safek about a Safek.