Leviticus 17;11

For the life of the flesh is in the blood, and I have given it for you on the altar to make atonement for your souls, for it is the blood that makes atonement by the life.

Hebrews 9:22

Indeed, under the law almost everything is purified with blood, and without the shedding of blood there is no forgiveness of sins.

Genesis 9:4

But you shall not eat flesh with its life, that is, its blood.