Answer #3: Both the Mishnah and Beraisa are referring to a married woman and a case of rape.

The Mishnah is referring to the wife of a Yisrael (where the woman remains permitted to her husband, and a lasting sign of the sin is only if a Mazmer is born of the union).

The Beraisa is referring to the wife of a Kohen (who becomes forbidden to her husband even when she is raped).

(Rav): "To the one who leaves and the one who comes, there is no peace" (Zecharyah 8:10) -- this refers to one who leaves Halachic discourse and goes to [learn] Scriptures, who has no more peace (for no Halachic ruling can be derived from the Scriptures alone).

(Shmuel): This refers to one who leaves Talmud in order to learn Mishnah (for no Halachic ruling can be derived from the Mishnah alone).

(R. Yochanan): This refers to one who even leaves the Talmud Yerushalmi to learn Talmud Bavli (which is much more difficult).

Heter Nedarim -- these laws "float in the air" and have no explicit verse to rely upon.

Hilchos Shabbos, Chagigos, Me'ilos -- these are like mountains hanging from a hair, for they have very few verses and many detailed laws.

The laws of Dinim (legal judgments), Avodos, Taharos and Tum'os, and Arayos have what to rely upon.

These are the body (essential part) of the Torah.

(Beraisa): Heter Nedarim does have a verse to rely upon.

(R. Eliezer): Heter Nedarim is learned from the repetition of "Ki Yafli" (Vayikra 27:2 and Bamidbar 6:2).

(R. Yehoshua): Heter Nedarim is learned from "Asher Nishbati b'Api" (Tehilim 95:11).

(R. Yitzchak): Heter Nedarim is learned from "Kol Nediv Libo" (Shemos 35:5).

(Chananyah): Heter Nedarim is learned from "Nishbati v'Akaymah" (Tehilim 119:106).

(Shmuel): Had I been there, I would have given a source better than all of theirs.

"Lo Yachel Devaro" ("he may not annul his word"; Bamidbar 30:3) -- he may not annul it, but others may annul it for him.

(Rava): All of the sources, except for Shmuel's, have questions on them.

This is what people mean when they say, "More effective is a single sharp pepper than a basket full of gourds."

Question: Why does the Mishnah say that Hilchos Shabbos have "very few verses" -- there are many verses commanding us to observe Shabbos!?

Answer: The Mishnah is referring to the principle that only a Meleches Machsheves is Asur mid'Oraisa, yet it is not written anywhere explicitly.

Question: Why does the Mishnah say that Hilchos Chagigos have "very few verses" -- there is an explicit source for Chagigos!?

Answer: We might have thought that the verse, "v'Chagosem Oso Chag la'Hashem" (Vayikra 23:41) means that they celebrated a party, and not that they brought Korbanos Chagigah.

Question: But there is a Gezeirah Shavah of "Midbar" (from Amos 5:25 to Shemos 5:1) which teaches clearly that they brought a Korban Chagigah!

Answer: Hilchos Chagigos are still "like mountains hanging from a hair," because a Gezeirah Shavah from Nevi'im to the Chumash cannot teach a Halachah d'Oraisa (it is only a Remez).

Question: Why does the Mishnah say that Hilchos Me'ilos have "very few verses" -- there is an explicit source for Me'ilah!?

Answer (Rava): The Mishnah is referring to a case when the owner remembers that the money is Hekdesh and rescinds his Shelichus, while the Shali'ach goes and uses the money of Hekdesh, inadvertently, to buy something for the owner -- the Shali'ach is Chayav for Me'ilah.

Question (R. Ashi): But that case is the same as every other case of Me'ilah, whereby a person inadvertently

Answer: In a normal case of Me'ilah, the person knows that there is money of Hekdesh (he just erred and took that money instead of taking non-Hekdesh money); while in this case, the Shali'ach had absolutely no idea that there was money of Hekdesh, and yet he is still Chayav -- that is why this Halachah is a "mountain suspended by a hair."