Leviticus 4:7-9

⁷Then he must put some of the blood on the projections at the corners of the altar where fragrant incense is burned in the Sacred Tent in the presence of Yahweh. The remaining part of the bull's blood that is still in the bowl, he must pour out at the base of the altar, where sacrifices are burned, at the entrance to the Sacred Tent.

⁸From that offering the Supreme Priest must separate these things from the bull that is to be burned: The fat that covers the inner parts of the bull or which is attached to them—

⁹the kidneys and the fat that is attached to them near the lower back muscle, and the fat that covers the liver.