Leviticus 3:13-17

3:13 lay his hand on its head, and slaughter it before the Meeting Tent, and the sons of Aaron must splash its blood against the altar’s sides. 3:14 Then he must present from it his offering as a gift to the Lord: the fat which covers the entrails and all the fat on the entrails, 3:15 the two kidneys with the fat on their sinews, and the protruding lobe on the liver (which he is to remove along with the kidneys). 3:16 Then the priest must offer them up in smoke on the altar as a food gift for a soothing aroma – all the fat belongs to the Lord. 3:17 This is a perpetual statute throughout your generations in all the places where you live: You must never eat any fat or any blood.’”

Leviticus 17:11

17:11 for the life of every living thing is in the blood. So I myself have assigned it to you on the altar to make atonement for your lives, for the blood makes atonement by means of the life.