Exodus 34:15-17

15otherwise you might make a covenant with the inhabitants of the land, and they would prostitute themselves with their gods and 1sacrifice to their gods, and someone 2might invite you 3to eat of his sacrifice, 16and 4you might take some of his daughters for your sons, and his daughters might prostitute themselves with their gods and cause your sons also to prostitute themselves with their gods. 175You shall not make for yourself any gods cast in metal.