1) THE THREE VERSES WHICH TEACH THAT ONE WHO WAS TAMEI MAY EAT TERUMAH AFTER "HE'EREV SHEMESH"
QUESTION: The Gemara lists three sources in the Torah for the law that one who was Tamei may eat Terumah after He'erev Shemesh (sundown) and does not need to wait until he brings his Korban the following day. The three sources are the verses: "He may not eat Kodshim Ad Asher Yit'har" (Vayikra 22:4), "u'Va ha'Shemesh v'Taher, and afterwards he may eat from the Kodshim" (Vayikra 22:7), and, "She may not touch any Kodesh... Ad Melos Yemei Taharah" (Vayikra 12:4). (See Chart.)
The Gemara explains that all three verses are necessary. The first verse, "Ad Asher Yit'har" (Vayikra 22:4) in the Parshah of Zav u'Metzora, does not suffice because if the Torah had written only that verse, one might have thought that he may eat Terumah after He'erev Shemesh only when he is not required to bring a Korban at all. When he is required to bring a Korban (such as a Zav who experienced three flows, or a Metzora Muchlat), he might have thought that he must wait until he brings his Korban the following day before he may eat Terumah. Therefore, another verse is necessary -- "Ad Melos Yemei Taharah" (Vayikra 12:4) -- to teach that he may eat Terumah at sundown and does not need to wait until he brings his Korban the following day.
The Gemara does not explain why the verse, "u'Va ha'Shemesh v'Taher" (Vayikra 22:7), is necessary. The verse of "Ad Melos" teaches that even when one is required to bring a Korban he may eat Terumah at sundown, before he brings the Korban. The verse of "Ad Asher Yit'har" teaches that Tevilah is required before one may eat Terumah (according to the first Tana who maintains that the verse refers to a Zav who experienced two flows and who becomes Tahor to eat Terumah and Kodshim without having to bring a Korban).
What new law does the verse "u'Va ha'Shemesh v'Taher" teach? When the Gemara says that the verse teaches the time of day (sunset) at which a person becomes Tahor to eat Terumah, it is merely explaining why the verse would have been necessary had the Torah not written the verse of "Ad Melos." When the Torah writes, "Ad Melos Yemei Taharah" -- until the end of the days of her Dam Taharah -- it thereby teaches that one becomes Tahor at the end of the day, and "u'Va ha'Shemesh v'Taher" is unnecessary.
TOSFOS (end of DH d'Iy) asks this question and offers two answers. However, neither answer is viable according to RASHI (74b, DH Kan l'Terumah, and Berachos 2b, DH Dilma), as the MAHARSHA and MAHARAM explain.
ANSWER: Perhaps the reason why the verse of "u'Va ha'Shemesh v'Taher" is necessary is as follows. The Gemara in Chulin (83a) teaches that for matters of Kodshim "the night follows the day" ("ha'Laylah Holech Achar ha'Yom"), as certain Korbanos may be eaten for a twenty-four period, comprised of a day and the night that follows it. Accordingly, when the verse which discusses a Yoledes says, "Ad Melos Yemei Taharah," it is unclear whether "the end of the day" refers to the arrival of morning (because this is a matter of Kodshim, for which the new day starts at sunrise), or whether "the end of the day" refers to the arrival of night. The verse of "u'Va ha'Shemesh v'Taher" teaches that the person becomes Tahor at sunset and not at sunrise. (M. Kornfeld)
2) THE PROOF THAT ONE VERSE REFERS TO "KODSHIM"
QUESTION: The Gemara lists three sources in the Torah for the law that one who was Tamei may eat Terumah after He'erev Shemesh (sundown) and does not need to wait until he brings his Korban the following day. The three sources are the verses: "He may not eat Kodshim Ad Asher Yit'har" (Vayikra 22:4), "u'Va ha'Shemesh v'Taher, and afterwards he may eat from the Kodshim" (Vayikra 22:7), and, "She may not touch any Kodesh... Ad Melos Yemei Taharah" (Vayikra 12:4). (See Chart.)
The Gemara explains that all three verses are necessary. The first verse, "Ad Asher Yit'har" (Vayikra 22:4) in the Parshah of Zav u'Metzora, does not suffice because if the Torah had written only that verse, one might have thought that he may eat Terumah after He'erev Shemesh only when he is not required to bring a Korban at all. When he is required to bring a Korban (such as a Zav who experienced three flows, or a Metzora Muchlat), he might have thought that he must wait until he brings his Korban the following day before he may eat Terumah. Therefore, another verse is necessary -- "Ad Melos Yemei Taharah" (Vayikra 12:4) -- to teach that he may eat Terumah at sundown and does not need to wait until he brings his Korban the following day.
The Gemara presents two ways of understanding the verse in the beginning of the Parshah of Zav u'Metzora. According to some Tana'im, the verse refers to a Zav who experienced two flows, and to a Metzora who is a Metzora Musgar. When the verse says that he must wait "Ad Asher Yit'har" -- "until he becomes Tahor," it means that at sundown, He'erev Shemesh, he becomes permitted to eat Terumah and Kodshim since he is not required to bring a Korban at all.
Another Tana (d'Vei Rebbi Yishmael) maintains that the verse refers to a Zav who experienced three flows, and to a Metzora who is a Metzora Muchlat. When the verse concludes that he must wait "until he becomes Tahor," it means that he must wait until he brings his Korban the following day. Before he brings his Korban he may not eat Kodshim.
RASHI explains that according to this Tana, the verse refers only to Kodshim. It cannot refer to Terumah, because a later verse (v. 7), "u'Va ha'Shemesh v'Taher," explicitly refers to Terumah and states that at sundown the person becomes Tahor. Since that verse teaches that one becomes Tahor at sundown for the purpose of eating Terumah, the verse which requires him to wait until he brings his Korban must refer to Kodshim and not to Terumah.
The Gemara's proof that the verse of "Ad Asher Yit'har" (Vayikra 22:4) refers to Kodshim is difficult to understand. According to d'Vei Rebbi Yishmael, the Torah there (Vayikra 22:4) refers to two separate groups of Teme'im. It first discusses a Zav who experienced three flows and a Metzora Muchlat, both of whom must bring Korbanos. The verse says that neither may eat Terumah "Ad Asher Yit'har," until he becomes Tahor by bringing his Korban. The verse then discusses all other Teme'im who do not bring a Korban (such as a Tamei Mes and a Ba'al Keri). The verse says "u'Va ha'Shemesh v'Taher" and permits him to eat Terumah at sundown. Consequently, the verse that says that one is Tahor at sundown refers to one who is not obligated to bring a Korban at all. Perhaps when he is obligated to bring a Korban (such as a Zav who experienced three flows), he may not eat Terumah until he brings his Korban just as he may not eat Kodshim until he brings his Korban. (The Gemara itself suggests this reasoning earlier.)
ANSWERS:
(a) The Gemara earlier mentions a third verse which clearly refers to Terumah: "She may not touch any Kodesh... Ad Melos Yemei Taharah" (Vayikra 12:4).
This verse implies that a Yoledes becomes permitted to eat Terumah at the end of the day ("Melos Yemei Taharah" -- "the end of the days of her Taharah"), sundown. She does not need to wait until the next day, when she brings her Korban, in order to eat Terumah. Since this verse clearly permits a person to eat Terumah at sundown even when he is obligated to bring a Korban, the verse of "Ad Asher Yit'har" which requires that one wait until he brings his Korban must refer to Kodshim and not to Terumah.
RASHI, however, gives a different explanation. Rashi writes that the source that one may eat Terumah after He'erev Shemesh and does not need to wait until he brings his Korban is the verse "u'Va ha'Shemesh v'Taher" (Vayikra 22:7) and not "Ad Melos Yemei Taharah" (Vayikra 12:4). Rashi's explanation is difficult to understand, because the verse "u'Va ha'Shemesh" does not refer to one who is required to bring a Korban.
(b) Apparently, Rashi has a different approach to the Gemara, which may be inferred from his words in Berachos (2b, DH Dilma). The Gemara there asserts that the phrase "u'Va ha'Shemesh v'Taher" may refer either to "the setting of the sun" or to "the coming of the sun," which Rashi explains to mean sunrise. It is clear from the Gemara that if the verse refers to sunrise, it is not the sunrise itself which makes the person Tahor; rather, the rising of the sun enables him to bring a Korban (since Korbanos may not be brought at night), and it is the Korban that makes him Tahor.
The Gemara concludes that the verse refers to sunset because the word "v'Taher" implies that he becomes Tahor passively and does not have to do any act, such as offer a Korban, to become Tahor (in contrast to the more common term, "va'Yetaher"). Hence, the verse means that the setting of the sun makes him Tahor. Moreover, the word "v'Taher" implies the setting of the sun and its disappearance under the horizon.
TOSFOS there rejects Rashi's explanation based on the Gemara here which derives from the verse "Ad Melos Yemei Taharah" (Vayikra 12:4) that one does not need to wait until he brings the Korban, but only until He'erev Shemesh, and the verse of "v'Taher" is not needed to teach this.
Rashi is consistent with his own reasoning in the Sugya here. Rashi understands that according to d'Vei Rebbi Yishmael, the Halachah that He'erev Shemesh permits one to eat Terumah is not derived from "Ad Melos Yemei Taharah" (Vayikra 12:4). "Ad Melos" may mean that she must wait until the morning and not until the evening (as mentioned in the previous Insight). If it means that she must wait until the morning, it likely refers to when she brings her Korban (as Rashi writes in Berachos). This is because d'Vei Rebbi Yishmael has a precedent in which the word "Yit'har" refers to bringing a Korban and not just to waiting for a certain time to arrive. Accordingly, the only source that one becomes Tahor at sundown is the verse, "u'Va ha'Shemesh v'Taher" (Vayikra 22:7). Although that verse discusses a person who does not need to bring a Korban, the Gemara in Berachos understands that the verse changed its wording from "va'Yetaher to "v'Taher" in order to teach that even one who is required to bring a Korban may eat Terumah before he brings the Korban, as long as He'erev Shemesh has arrived.
What, then, does the verse "Ad Melos" teach? Why is that verse necessary? The answer is that one might have thought that the Yoledes becomes Tahor after the first evening passes after she gives birth. The verse teaches that she must wait until the last evening after all of her days of Taharah have passed. (That is, one would not have known the Halachah that she is a "Tevulas Yom Aruch.")
This explains why Rashi here writes that according to d'Vei Rebbi Yishmael, the verse of "u'Va ha'Shemesh v'Taher" (Vayikra 22:7) is the source that one who is Tamei -- and who needs to bring a Korban -- becomes Tahor to eat Terumah at sundown. (M. Kornfeld)