Joshua 23:12-13

For if you go back, joining yourselves to the rest of these nations who are still among you, getting married to them and living with them and they with you: Then you may be certain that the Lord your God will not go on driving these nations out from before you; but they will become a danger and a cause of sin to you, a whip for your sides and thorns in your eyes, till you are cut off from this good land which the Lord your God has given you.