Exodus 29:28

29:28 It is to belong to Aaron and to his sons from the Israelites, by a perpetual ordinance, for it is a contribution. It is to be a contribution from the Israelites from their peace offerings, their contribution to the Lord.

Exodus 32:6

32:6 So they got up early on the next day and offered up burnt offerings and brought peace offerings, and the people sat down to eat and drink, and they rose up to play.