Leviticus 3:3-5

And he is to give of the peace-offering, as an offering made by fire to the Lord; the fat covering the inside parts and all the fat on the inside parts, And the two kidneys, and the fat on them, which is by the top part of the legs, and the fat joining the liver and the kidneys, he is to take away; That it may be burned by Aaron's sons on the altar, on the burned offering which is on the wood on the fire: it is an offering made by fire of a sweet smell to the Lord.