Midrasch zu Schemot 29:14

12) (Vayikra 8:14): ("And he presented the bullock of the sin-offering, and Aaron and his sons placed their hands on the head of the bullock of the sin-offering.") "And he presented the bullock of the sin-offering": In the beginning, it was not called "the bullock of the sin-offering," viz. (Shemoth 29:1): "And this is the thing that you shall do to them to sanctify them to minister unto Me: Take one young bullock and rams, etc." In its specific accounting it is called "the bullock of the sin-offering," viz. (Shemoth 29:14): "And the flesh of the bullock and its hide and its waste you shall burn in a fire outside the camp — it is a sin-offering." We do not know whether this refers to the sin-offering of Aaron and his sons or to the communal sin-offering. "Take Aaron and his sons with him … and the bullock of the sin-offering" (Vayikra 8:2) tells us that it is the sin-offering of Aaron and his sons and not the communal sin-offering.