Charles Ellicott Commentary Exodus 29:18

"And thou shalt burn the whole ram upon the altar: it is a burnt-offering unto Jehovah; it is a sweet savor, an offering made by fire unto Jehovah." — Exodus 29:18 (ASV)

Thou shalt burn the whole ram upon the altar. —A burnt offering, as representing self-sacrifice, was entirely acceptable to God; the whole might be consumed upon the altar. It was otherwise with sin offerings, of which only certain parts could be thus offered. (Compare to Exodus 29:14, mentioned above; and see Leviticus 4:12, Leviticus 4:21, and other similar passages.)

A sweet savour. —Compare to Genesis 8:21 and the note on that verse. It was a general heathen notion that the gods were actually delighted with the odor of the sacrifices offered to them; but there are no just grounds for accusing the Hebrews of such coarse and materialistic ideas. The expression, as used in this place, in Genesis 8:21, and in Leviticus and Numbers repeatedly, is metaphorical. (Compare to Exodus 5:21.)