Albert Barnes Commentary Leviticus 3:5

"And Aaron`s sons shall burn it on the altar upon the burnt-offering, which is upon the wood that is on the fire: it is an offering made by fire, of a sweet savor unto Jehovah." — Leviticus 3:5 (ASV)

Upon the burnt sacrifice - Upon the ashes of the continual burnt-offering (Exodus 29:38), in accordance with (Leviticus 6:12).