Leviticus 7:4-6

⁴and the two kidneys, and the fat that is on them, which is by the flanks, and the net above the liver, which he shall take away as far as the kidneys.

⁵And the priest shall burn them on the altar, an offering by fire to Jehovah: it is a trespass-offering.

⁶Every male among the priests shall eat thereof; in a holy place shall it be eaten: it is most holy.