Charles Ellicott Commentary Numbers 18:9

"This shall be thine of the most holy things, [reserved] from the fire: every oblation of theirs, even every meal-offering of theirs, and every sin-offering of theirs, and every trespass-offering of theirs, which they shall render unto me, shall be most holy for thee and for thy sons." — Numbers 18:9 (ASV)

From the fire.— i.e., from the fire which was kindled upon the altar of burnt offering.

Every oblation of theirs, every meat offering of theirs ... — Or, every oblation of theirs for all their meat offerings, and for all their sin offerings, and for all their trespass offerings (or, guilt offerings).