Joshua 23:11-13

So be very careful and watchful of yourselves to love the LORD your God. For if you ever turn back and cling to the rest of these nations, these that are left among you, and intermarry with them, so that you associate with them and they with you, know and understand with certainty that the LORD your God will not continue to drive these nations out from before you; but they will be a snare and trap to you, and a whip on your sides and thorns in your eyes, until you perish from this good land which the LORD your God has given you.