(Mishnah): Similarly, one who left Yerushalayim and remembered that he has Kodesh meat (that may not be removed from Yerushalayim), if he had passed the point where the Beis ha'Mikdash was still visible, he burns it there; if not, he must return and burn it in front of the Beis ha'Mikdash using wood from the woodpile of the Mizbeach

Question: For which quantity must one return?

Answer: R. Meir says that for both cases the quantity is a k'Zayis. R. Yehudah says that both are a k'Beitzah (egg-sized amount). Chachamim say that Kodesh meat is a k'Zayis and Chametz is a k'Beitzah.

(R. Simon quoting R''YSL): The Pasuk states (Zecharia 14,20), "On that day there shall be on the bells (Matzilos) of horses Holy...etc.'' - this refers to the distance that the horse runs and does not make a shadow (tzail) (i.e. until noon - when the shade is only underneath the horse and is difficult to see. This will be the limits of the extension of Yerushalayim in days to come.)

Question (R. Shmuel bar Rav Yitzchak): If it is Kodesh, burn it in its place within Yerushalayim where it can be eaten. (Why does the Mishnah require burning it in front of the Beis HaMikdash?)

Answer: As even in Yerushalayim they would burn it in front of the Beis HaMikdash from the wood of the woodpile.

Question: Is this Pesul of taking the meat out of Yerushalayim considered like meat that became Tamei outside or inside the Temple courtyard? (R. Akiva teaches in Maseches Shekalim that the item is burned in the place that it became Tamei.)

Answer (R. Yosa): Since its Tum'ah came about because of its location, it is considered like meat that became Tamei outside.

Objection (R. Yosi bar R. Bun): The Torah considers it to be tahor and it was the Rabbis who decreed upon it Tum'ah. Is it not enough that you decreed upon it Tum'ah, that you want to give it a status of having become Tamei outside instead of inside?

There is a Beraisa that switches the opinions of R. Meir and R. Yehudah of our Mishnah. R. Yaakov bar Acha quoting R. Yasi taught like our Mishnah.

(R. Yudan): A sign (to remember these opinions) is in the Mishnah in Maseches Berachos - What is the minimum amount of bread upon which one makes a zimun? R. Meir says a k'Zayis and R. Yehudah says a k'Beitzah.

(Beraisa): For less than this quantity, we do not trouble him to return. According to Chachamim, why is Kodesh different from Chametz (that the amount for Kodesh is a k'Zayis and Chametz is a k'Beitzah)? Chametz can be annulled (thereby preventing a Torah transgression - so the amount is more lenient).

Question: It is for Kodesh meat that we have stated than less than that amount, we do not trouble him to return. What is the source of this law for Chametz? (Alternatively, what is the source that one may also burn Chametz using wood from the woodpile?)

Answer (R. Yosi bar R. Bun): From our Mishnah that stated, "Similarly, one who left Yerushalayim'' - this teaches that whatever applies to this applies to that.