Gemara

(Mishnah - R. Yehudah): The Shi'ur for Cheres is to put between pillars [so they will not lean];

R. Meir says, it must be big enough to stoke coals;

R. Yosi says, it must hold a Revi'is.

R. Meir: There is a hint, but not a proof for my opinion - "v'Lo Yimatzei vi'Mchitaso Cheres Lachtos Esh mi'Yakod."

R. Yosi: That is not a proof! (The verse says that even my Shi'ur is important --) "v'Lachsof Mayim mi'Geve"!

86a (Mishnah) Question: What is the source that anointing is [forbidden] like drinking on Yom Kipur?

Answer: Even though there is not a proof, there is a Zecher (commemoration). It says "va'Tavo cha'Mayim b'Kirbo vecha'Shemen b'Atzmosav."

Yoma 76b - Question: What is the source that bathing is forbidden on Yom Kipur?

Answer #1: It says "va'Tavo cha'Mayim b'Kirbo vecha'Shemen b'Atzmosav."

Question: Perhaps this refers to drinking water!

Answer: It is like oil, which is [put] externally [on the body].

Objection: A Tana expounds oppositely (in the Mishnah in Shabbos)!

Answer #2: Rather, we learn from "v'Soch Lo Sachti."

Rishonim

Rambam (Hilchos Shabbos 21:1): The Torah says "Tishbos" - one must cease even from things that are not Melachah. Chachamim forbade many things due to Shevus. Some resemble Melachos, and some are decrees lest one come to an Isur Skilah.

Lechem Mishneh: In one Perush, the Magid Mishneh says that the Torah forbade only a full Shi'ur of Melachah. "Tishbos" forbids Chetzi Shi'ur. Chachamim forbade many things outside the category of Shevus. His other Perush holds that the Torah forbade only proper Melachos. Chachamim used the verse to support Shevus.

Perush ha'Mishnayos (introduction, DH v'Cha'asher): The Gemara said that Shi'urim are a tradition from Moshe from Sinai. It challenged this, for the verse "Eretz Chitah u'Se'orah..." hints to Shi'urim! It answered that they are a tradition from Sinai that cannot be expounded at all. The verse is a mere Asmachta. It is a Siman to help remember them. Whenever it says that a verse is an Asmachta, it means like this.

Tosfos (82a DH Amar): Our Perek begins with Tum'ah of Avodah Zarah, for which we bring Drashos that are Asmachtos from verses close to the verses used for asm9 at the end of the previous Perek.

Tosfos (86a DH Af): We say that it is not a real proof, for the verse discusses bathing, and not drinking. It connotes that water is like oil, which is [anointed] externally. The Ri asked that in Yoma, we tried to learn from this verse that [not] bathing is called Inuy (affliction), but rejected this, for a Tana expounds it oppositely, that anointing [with oil] is like drinking [water]! Our Tana said that it is a mere Zecher! The Ri explains that if it were a real proof that anointing is like drinking, the Tana should not make even a Zecher [oppositely].

Rashi (Pesachim 7b DH Zecher): This is not a real proof. It is a mere Asmachta, for we do not learn Divrei Torah from Divrei Kabalah (Nevi'im and Kesuvim).

Ritva (Rosh Hashanah 16a): The Gemara says "Hash-m said 'say in front of Me Malchuyos, Zichronos and Shofaros...'" even though the verses of Malchuyos are mid'Rabanan. Since the Torah said "Zichron Teru'ah", we learn that it is proper to mention verses of Teru'ah and Zichronos. We learn Malchuyos like Chachamim expounded the repetition "v'Hayah Lachem l'Zikaron Lifnei Elokeichem Ani Hash-m Elokeichem" to teach that whenever we mention Zichronos, we mention also Malchuyos next to them. This verse was Chachamim's support to enact verses of Teki'ah. Whatever has an Asmachta from a verse, Hash-m aroused that it is proper to do so, but he did not impose it for a Chiyuv. He left it to Chachamim [to enact it]. This is clear, unlike those who say that an Asmachta is like a Siman that Chachamim gave, but not that the Torah intended for this. Such words should not be heard. This is heresy! Rather, the Torah aroused it, and left it to Chachamim to enact if they want - "v'Asisa Al Pi ha'Davar Asher Yagidu Lecha." Therefore, we find that Chachamim gave a proof, Zecher or Asmachta to their words from the Torah. I.e. they were not Mechadesh it by themselves. The entire Oral Torah is hinted to in the written Torah, which is Temimah (complete). It does not lack anything.

Kol Mevaser (2:22): The Ritva says that some say that an Asmachta is like a Siman Chachamim gave, but not that the Torah intended for this, and this is heresy. He does not refer to the Rambam. He did not see the Rambam's introduction to Perush ha'Mishnayos. The Rambam rules over all hidden parts of the Bavli, Yerushalmi, and Tosefta. He is the Rebbi of all Yisrael in Halachah. Even when the Ritva argues with him, he would not belittle the Rambam's honor and call his opinion heresy. Rather, the Ritva refers to the Ibn Ezra, who says so in several places. Also the Maharshal [in his introduction to Yam Shel Shlomo on Bava Kama] says that the Ibn Ezra was not a Ba'al Talmud, and often explains unlike the Halachah, and thereby supports heretics, Tzedukim and people of weak faith. Also the Ya'avetz harshly criticized him. The Abarvanel honors the Ibn Ezra, yet regarding Shifchah Charufah he wrote "it is astounding that the Ibn Ezra was enticed by the Kara'ites and their Perushim [and wrote that Shifchah Charufah is an Amah Ivriyah after Yi'ud]. The Ohr ha'Chayim calls the Ibn Ezra a Gaon, yet regarding a yellow hair he says "if we will argue with Chazal and explain according to Arabic, like the Ibn Ezra, we falsify Torah and support those who seek to belittle Torah. Such Perushim should not be said."

Question: Even if the Ritva did not see the introduction to Perush ha'Mishnayos, he saw and cites Moreh Nevuchim! (Also there the Rambam explains that Asmachta is like a Siman.)

Answer (Kol Mevaser): There is different, for there he discusses an Agada. We read "you should have a shovel with Azenecha (your weapons)" like Oznecha (your ears), to teach that one should stick his finger in his ear if he hears something improper (Kesuvos 5a). All agree that this is not the simple reading of the verse. It is like poetic license and Asmachta. Also the Rashba (Chidushei Agados Berachos 32a, brought in ha'Kosev in Ein Yakov, p.63b) says so. The Ramban and Chizkuni say that if a Halachah does not apply to all generations, since there is no practical difference, just we seek to explain the verse, early Meforshim allowed themselves to explain Peshat unlike Chazal, like in Agada.

Tosfos (Menachos 92b DH Girsa): One Perush in Rashi says that R. Yehudah has no tradition from Sinai that only two Korbanos Tzibur require Semichah. It is a mere Girsa (text). He learns them from verses. This is difficult, for above (62b) we tried to learn Semichah for Zivchei Shalmei Tzibur from a Kal va'Chomer, and rejected this, because "Gemiri (we have a tradition) that there are only two Semichos b'Tzibur. We can say that that is like R. Shimon, who has a tradition. R. Yehudah says that it is a mere Girsa. Rashi's other text says that it is a mere Girsa, i.e. the verses are a mere Asmachta, to be a Siman to remember the text.

Ritva (Yoma 76b DH Af): Why isn't this a proof? If it is because it is only mid'Rabanan, and the verse is a mere Asmachta, we say that many Drashos are mere Asmachtos, yet we do not say that it is not a proof! I answer that the verse does not discuss drinking and anointing. It merely gives a Mashal for a curse entering the innards of Resha'im. One cannot bring a proof from a verse that speaks like a Mashal. Tosfos says that it is only a hint because one could explain oppositely, like Rav Zutra. This is wrong.

Ramban (Vayikra 25:9): Rashi cites a Beraisa that says that Teki'ah of Yom Kipur [of Yovel] overrides Shabbos everywhere, but Teki'ah of Rosh Hashanah overrides Shabbos only in Beis Din. Granted, the entire Talmud is clear to Rashi, but this is misleading to those who do not know that Teki'ah even not for a Mitzvah is permitted on Shabbos, for it is a Chachmah, and not a Melachah. The Torah permits Teki'ah on Shabbos of Rosh Hashanah or Yom Kipur everywhere. Chachamim decreed not to on Shabbos Rosh Hashanah, lest one carry a Shofar to learn how to blow. Regarding Yom Kipur, we do not distinguish whether or not it is on Shabbos, for Yom Kipur is like Shabbos regarding all Melachos.

Melamed ha'Talmidim (Yom Matan Torah DH veha'Mashal): Torah is found only in one who exerts himself until the time of death. Chachamim gave a support from a verse ("Zos ha'Torah Adam Ki Yamus b'Ohel"). This greatly helps the masses who hear this to see the truth of this and know in the heart that the Torah commanded about this. Most Drashos in the Talmud are based on this strategy.

Acharonim

Kol Mevaser: Do not say derive from Menachos 92b that Tosfos holds like the Rambam regarding Asmachta. In Chulin 7a, Tosfos says that the Yerushalmi says that Ma'aser of vegetables is mid'Rabanan, i.e. there is no Asmachta from a verse, like there is for Ma'aser of fruits. He says similarly in several other places. In Menachos, it is not a proper Asmachta. It is a mere Siman. This is why the Gemara said 'a mere Girsa' [and not a mere Asmachta, like it normally says], since the verse does not connote like this so much. The Ritva (Nidah 38b DH Herayon) says so, and Perush ha'Mishnayos (Shabbos 9:5) says 'this is a weak Asmachta, like a Siman.' This implies that a proper Asmachta is more than a mere Siman. The Magid Mishneh equates the Rambam to the Ramban on Chumash. In Devarim (14:12), the Ramban said that some Beraisos in Toras Kohanim and Sifri are Asmachtos, and they are misleading. The Ritva in Yoma distinguishes between an Asmachta and a Zecher. Tosfos (82a) connotes that there is no difference.

Kuntres Divrei Sofrim (in Kovetz Shi'urim, 1:17): The Torah obligated Bnei Yisrael to separate from their wives only two days before Matan Torah. The third day was only mid'Rabanan. The verse or Kal va'Chomer is a mere Asmachta. Moshe decided like Hash-m's desire. Hash-m wanted this, just he did not explicitly command it. We can say the same about all Mitzvos and Isurim mid'Rabanan. E.g. also Hash-m wanted to forbid Sheniyos (secondary Arayos), just He did not explicitly command about them. This is why we must fulfill mid'Rabanan laws, because it is Hash-m's will. He agreed with Chachamim. However, they are lighter than what the Torah explicitly commands about.