Exodus 32:5
5 And Aaron looked and built an altar before it; and Aaron made a proclamation and said, “Tomorrow shall be a feast to Yahweh.”
Exodus 32:8
8 They have quickly turned aside from the way which I commanded them. They have made for themselves a molten calf and have worshiped it and have sacrificed to it and said, ‘These are your gods, O Israel, who brought you up from the land of Egypt!’”