Deuteronomy 7:2-5

2And when the LORD thy God shall deliver them before thee; thou shalt smite them, and utterly destroy them; thou shalt make no covenant with them, nor show mercy to them:

3Neither shalt thou make marriages with them; thy daughter thou shalt not give to his son, nor his daughter shalt thou take to thy son.

4For they will turn away thy son from following me, that they may serve other gods: so will the anger of the LORD be kindled against you, and destroy thee suddenly.

5But thus shall ye deal with them; ye shall destroy their altars, and break down their images, and cut down their groves, and burn their graven images with fire.1