Leviticus 17:6

17:6 The priest is to splash the blood on the altar of the Lord at the entrance of the Meeting Tent, and offer the fat up in smoke for a soothing aroma to the Lord.

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.