Deuteronomy 7:2-5

2When the Lord your God hands these nations over to you and you conquer them, you must completely destroy them. Make no treaties with them and show them no mercy.

3You must not intermarry with them. Do not let your daughters and sons marry their sons and daughters,

4for they will lead your children away from me to worship other gods. Then the anger of the Lord will burn against you, and he will quickly destroy you.

5This is what you must do. You must break down their pagan altars and shatter their sacred pillars. Cut down their Asherah poles and burn their idols.