Deuteronomy 9:4

Speak not thou in thine heart,.... Never once think within thyself, or give way to such a vain imagination, and please thyself with it:

after that the Lord thy God hath cast them out from before thee; to make way for the Israelites, and put them into the possession of their land; which is to be ascribed not to them, but to the Lord:

saying, for my righteousness the Lord hath brought me in to possess this land; such a thought as this was not to be secretly cherished in their hearts, and much less expressed with their lips; nothing being more foreign from truth than this, and yet a notion they were prone to entertain. They were always a people, more or less, from first to last, tainted with a conceit of their own righteousness, and goodness, which they laboured to establish, and were ready to attribute all the good things to it they enjoyed, and nothing is more natural to men, than to fancy they shall be brought to the heavenly Canaan by and for their own righteousness; which is contrary to the perfections of God, his purity, holiness, and justice, which can never admit of an imperfect righteousness in the room of a perfect one; to justify anyone thereby, is contrary to the Gospel scheme of salvation; which is not by works of righteousness men have done, but by the grace and mercy of God through Christ; it would make useless, null, and void, the righteousness of Christ, which only can justify men in the sight of God, give a title to heaven and happiness, and an abundant entrance into it; and would occasion boasting, not only in the present state, but even in heaven itself; whereas the scheme of salvation is so framed and fixed, that there may be no room for boasting, here or hereafter, see Romans 3:27,

but for the wickedness of these nations the Lord doth drive them out from before thee; namely, their idolatry, incest, and other notorious crimes; see Leviticus 18:3, which sufficiently justifies God in all his dealings with these nations.