Deuteronomy 7:2-4

2and when the Lord your God gives them over to you and you defeat them, then you shall utterly destroy them. You shall not make a covenant (treaty) with them nor show mercy and compassion to them.

3You shall not intermarry with them; you shall not give your daughter to his son, nor shall you take his daughter for your son;

4for they will turn your sons away from following Me to serve other gods; then the anger of the Lord will be kindled and burn against you and He will quickly destroy you.