Joshua 23:3, 7-8, 12-13

   3 And ye have seen all that the LORD your God hath done unto all these nations because of you; for the LORD your God [is] he that hath fought for you. ...

   7 That ye come not among these nations, these that remain among you; neither make mention of the name of their gods, nor cause to swear [by them], neither serve them, nor bow yourselves unto them: But cleave unto the LORD your God, as ye have done unto this day. ...

   12 Else if ye do in any wise go back, and cleave unto the remnant of these nations, [even] these that remain among you, and shall make marriages with them, and go in unto them, and they to you: Know for a certainty that the LORD your God will no more drive out [any of] these nations from before you; but they shall be snares and traps unto you, and scourges in your sides, and thorns in your eyes, until ye perish from off this good land which the LORD your God hath given you.