12 “But if you do at all go back, and hold fast to the remnant of these nations, even these who remain among you, and make marriages with them, and go in to them, and they to you; 13 know for a certainty that Yahweh your God will no longer drive these nations from out of your sight; but they shall be a snare and a trap to you, a scourge in your sides, and thorns in your eyes, until you perish from off this good land which Yahweh your God has given you.

Matthew Henry's Commentary on Joshua 23:12-13

Commentary on Joshua 23:11-16

(Read Joshua 23:11-16)

Would we cleave to the Lord, we must always stand upon our guard, for many a soul is lost through carelessness. Love the Lord your God, and you will not leave him. Has God been thus true to you? Be not you false to him. He is faithful that has promised, Hebrews 10:23. The experience of every Christian witnesses the same truth. Conflicts may have been severe and long, trials great and many; but at the last he will acknowledge that goodness and mercy followed him all the days of his life. Joshua states the fatal consequences of going back; know for a certainty it will be your ruin. The first step would be, friendship with idolaters; the next would be, marrying with them; the end of that would be, serving their gods. Thus the way of sin is down-hill, and those who have fellowship with sinners, cannot avoid having fellowship with sin. He describes the destruction he warns them of. The goodness of the heavenly Canaan, and the free and sure grant God has made of it, will add to the misery of those who shall for ever be shut out from it. Nothing will make them see how wretched they are, so much, as to see how happy they might have been. Let us watch and pray against temptation. Let us trust in God's faithfulness, love, and power; let us plead his promises, and cleave to his commandments, then we shall be happy in life, in death, and for ever.