Deuteronomy 7:3-5

New Century Version

³ Do not marry any of them, or let your daughters marry their sons, or let your sons marry their daughters. ⁴ If you do, those people will turn your children away from me, to begin serving other gods. Then the Lord will be very angry with you, and he will quickly destroy you. ⁵ This is what you must do to those people: Tear down their altars, smash their holy stone pillars, cut down their Asherah idols, and burn their idols in the fire.