Charles Ellicott Commentary Leviticus 6:25

"Speak unto Aaron and to his sons, saying, This is the law of the sin-offering: in the place where the burnt-offering is killed shall the sin-offering be killed before Jehovah: it is most holy." — Leviticus 6:25 (ASV)

In the place where the burnt offering is killed. —That is, the north side of the altar. (See Leviticus 1:11.)

It is most holy. —That is, the sin offering belongs to the class of sacrifices which is most holy. (See Leviticus 2:3.)