Divrei Torah on the weekly portions
"Any priest fit to offer it may eat the sin offering; it shall be eaten in a holy place, in the courtyard of the Tent of Meeting" (VaYikra 6:19).
This law that the holiest sacrifices must be eaten in the Temple courtyard is mentioned in the Mishnah "Eizeihu Mekoman" (Zevachim 5:3): "… And they are eaten within the hangings by the male priests."
The difficulty with the wording of this Mishnah is that the hangings were used in the Tabernacle as the walls of the courtyard. This Mishnah, however, is referring to the service in the Temple (some years after the Tabernacle) where the walls were made of stone!
The Vilna Ga’on taught that this chapter of Mishnah was specifically chosen to be part of the daily morning prayers because of its unique feature that there is no dispute in any of the laws mentioned. The Vilna Ga’on added that the words of this chapter are the exact words uttered by Moshe when he taught these laws to the Israelites.
This is the reason why the Mishnah stipulates that the sacrifices must be eaten "within the hangings", and not within the walls, because Moshe was referring to the Tabernacle.