Rashi on Leviticus 4:12/רש"י על ויקרא ד׳:י״ב

1אל מקום טהור [EVEN THE WHOLE BULLOCK SHALL HE BRING FORTH WITHOUT THE CAMP] UNTO A CLEAN PLACE — Because there was outside the city (Jerusalem) a place intended for depositing unclean things viz., to cast there the plague-stricken stones (cf. Leviticus 14:45) and to serve as a place of burial, Scripture was compelled to state regarding this term “without the camp” — which in the case of Jerusalem, is identical with: “without the city” — that the place where it was to be burnt shall be a clean one.

2מחוץ למחנה WITHOUT THE CAMP — i. e. without the three camps (מחנה שכינה, מחנה לויה ומחנה ישראל) ; and, in the case of the “House of Eternity” (the Temple), it was to be brought forth without the city, just as our Rabbis have explained it in Treatise Yoma 68a and in Treatise Sanhedrin 42b.

3אל שפך הדשן means: to the place where the ashes that were removed from the altar were cast, as it is said (Leviticus 6:4) “and he shall bring out the ashes without the camp”.

4על שפך הדשן UPON THE PLACE FOR SHEDDING THE ASHES [SHALL IT BE BURNT] — This is something which need not have been stated (since it says immediately before, that it shall be brought forth to this spot), but it is intended to teach that even if at the time there happen to be no ashes there, the bullock shall nevertheless be burnt there (Sifra, Vayikra Dibbura d'Chovah, Chapter 5 5; Pesachim 75b).