After Moses anoints the Tent of Appointed Meeting and the Priests who will officiate there, God speaks to him:
Explain to the sons of Israel the ways of bringing offerings to God. There will be offerings of animals and grains and fruit. Animals for sacrifice shall be male and without blemish. These animals shall be killed and washed and burned so each shall smoke on the altar in the Tent of Appointed Meeting. This will be for an ascent offering, an offering made by fire in expression of compliance to God and to make atonement before God.