Exod 32:4-6

4He took the gold from them, formed it in a mold, and cast an image of a calf; and they said, “These are your gods, O Israel, who brought you up out of the land of Egypt!”5When Aaron saw this, he built an altar before it; and Aaron made proclamation and said, “Tomorrow shall be a festival to the Lord.”6They rose early the next day, and offered burnt offerings and brought sacrifices of well-being; and the people sat down to eat and drink, and rose up to revel.