Deuteronomy 7:3-5

Nor shall you make marriages with them. You shall not give your daughter to their son, nor take their daughter for your son. For they will turn your sons away from following Me, to serve other gods; so the anger of the LORD will be aroused against you and destroy you suddenly. But thus you shall deal with them: you shall destroy their altars, and break down their sacred pillars, and cut down their wooden images, and burn their carved images with fire.