OPINIONS: The Mishnah (62a) lists the seven substances that are passed over a stain in order to determine whether it is a bloodstain. One of those substances is "Rok Tafel," or "tasteless saliva." The Mishnah says that saliva is considered Tafel if the person "did not taste anything."

(a) How long must one not eat in order for his saliva to be considered Rok Tafel? The Gemara says that he must not eat "miba'Erev," from the evening. What does this mean?

(b) Furthermore, until when in the day is one's saliva considered Rok Tafel? The Gemara says, "Until one speaks most of his speech of the first three hours of the day." What does this mean?

(a) The Rishonim give various interpretations for the Gemara's statement that saliva is considered Tafel when one does not eat "from the evening."

1. RASHI explains that this means from the time one goes to sleep (before midnight, in accordance with Rabah bar bar Chanah's condition that the person be asleep at midnight).

2. The RAMBAM (Hilchos Isurei Bi'ah 9:38) explains that this means that he must not eat from the beginning of the night.

(b) Rashi and the Rambam also differ with regard to how long into the day one's saliva is considered Rok Tafel.

1. Rashi explains that the Gemara means until a person speaks most of what one usually speaks during the first three hours of the day. (Speaking dulls the sharpness of the saliva.)

2. The Rambam explains that until the end of the third hour of the day, one's saliva is Rok Tafel. What does the Gemara mean when it says until one speaks "Rov Diburo" ("most of his speech")?

The Rambam's text of the Gemara apparently did not have the word "Shel" in his text ("most of his speech of the first three hours of the day"). Rather, the words "most of his speech" are explaining why Rok Tafel lasts only for the first three hours of the day. The Rambam understands "Rov" to mean "a lot" and not "most." During the first three hours of the day, a person speaks a lot and this dulls the sharpness of his saliva. (It does not mean that one must speak a certain amount, as Rashi explains.)

QUESTION: Rebbi Yehudah says that in order for Mei Gerisin to serve as an effective cleansing agent, it must be boiling hot, but not have any salt added to it. The words he uses are "Over she'Yiten b'Socho Melach" -- literally, "ahead of when he puts into it salt." Why does Rebbi Yehudah not say simply, "Kodem she'Yiten b'Socho Melach" -- "before he puts into it salt"?

ANSWER: The NIMUKEI HA'GRIV points out that whenever the word "Over" is used, it means immediately before, or pre-empting, another occurrence. Rebbi Yehudah is explaining how hot the Mei Gerisin must be. The Mei Gerisin must be so hot that it is at the point at which salt would normally be put into it, and "Over she'Yiten" means that it is used to test the stain right before putting salt into it. One uses the Mei Gerisin immediately before the salting. This excludes using the Mei Gerisin long before it is hot enough for salt to be put into it.

The NIMUKEI YOSEF (Hilchos Tefilin, DH Over) explains that this is also what the Gemara means when it says that a blessing for a Mitzvah must be recited "Over l'Asiyasan," or "ahead of" the Mitzvah that is to be performed (Pesachim 7b, Sukah 39a, Megilah 21b; see Insights there). One begins the action of the Mitzvah and recites the blessing right before the actual fulfillment of the Mitzvah.

This meaning of "Over" is evident from the verse that is cited as a proof for its meaning: "And Achima'atz ran... and overtook (va'Ya'avor) the Kushi" (Shmuel II 18:23). The verse says that the Kushi was ahead of Achima'atz, but Achima'atz overtook him and went before him.

OPINIONS: Rebbi Yehudah and Rebbi Yosi disagree about how long a husband and wife must separate when her expected time of bleeding arrives. Rebbi Yosi maintains that they separate only for the hour in which she expects to bleed. Rebbi Yehudah says that they must separate for the entire twelve-hour period ("Onah") during which she expects to bleed. Rava rules in accordance with Rebbi Yehudah, and this is the Halachah as well. The separation period comprises an entire twelve-hour period, and not just the hour.

The Rishonim point out that there are two cases in which Rebbi Yehudah agrees that the separation period is only for the time that she expects to see blood, and not for the entire twelve-hour period.

(a) The ROSH (9:2) writes that if a woman sees blood at night and the bleeding continues into the day, her separation period is at night (the twelve-hour period during which her bleeding began), and she does not have to separate from her husband during the entire twelve-hour daytime period. She must separate from him only during the time that she actually saw the blood during the day.

(b) The RA'AVAD (in Ba'alei ha'Nefesh) proves that in a case in which a woman has established her Veses to be an "hourly" one -- that is, every month she bleeds at the same hour of the day of her Veses, even Rebbi Yehudah agrees that she does not have to separate from her husband for the entire twelve-hour period of that Veses, but only for the hour. (See BEIS YOSEF YD 189 and DIVREI CHAMUDOS 9:15.)