Charles Ellicott Commentary Leviticus 16:25

"And the fat of the sin-offering shall he burn upon the altar." — Leviticus 16:25 (ASV)

And the fat of the sin offering. —That is, the fat of the internal parts of both the young bull and the goat , which constituted the sin offering, as well as the fat of the other goat (which was the priest’s sin offering), was to be burned upon the brazen altar of burnt offering in the courtyard. (See Leviticus 4:8-10.)