Leviticus 9:18-20

And he put to death the ox and the sheep, which were the peace-offerings for the people; and Aaron's sons gave him the blood and he put some of it on and round the altar; And as for the fat of the ox and the fat tail of the sheep and the fat covering the inside parts and the kidneys and the fat on the liver; They put the fat on the breasts, and the fat was burned on the altar.