1. How he describes the apostasy which he warns them against. The steps of it would be (v. 12) growing intimate with idolaters, who would craftily wheedle them, and insinuate themselves into their acquaintance, now that they had become lords of the country, to serve their own ends. The next step would be intermarrying with them, drawn to it by their artifices, who would be glad to bestow their children upon these wealthy Israelites. And the consequence of that would be (v. 16) serving other gods (which were pretended to be the ancient deities of the country) and bowing down to them. Thus the way of sin is down-hill, and those who have fellowship with sinners cannot avoid having fellowship with sin. This he represents, (1.) As a base and shameful desertion; "it is going back from what you have so well begun," v. 12. (2.) As a most perfidious breach of promise (v. 16): "It is a transgression of the covenant of the Lord your God, which he commanded you, and which you yourselves set your hand to." Other sins were transgressions of the law God commanded them, but this was a transgression of the covenant he commanded them, and amounted to a breach of the relation between God and them and a forfeiture of all the benefits of the covenant.