Deuteronomy 7:2-5

2and when the Lord your God has delivered them over to you and you have defeated them, then you must destroy them totally. Make no treaty with them, and show them no mercy.

3Do not intermarry with them. Do not give your daughters to their sons or take their daughters for your sons,

4for they will turn your children away from following me to serve other gods, and the Lord’s anger will burn against you and will quickly destroy you.

5This is what you are to do to them: Break down their altars, smash their sacred stones, cut down their Asherah poles and burn their idols in the fire.