(4) But for the wickedness.--"Say not in thine heart, 'in my righteousness,' when it is in consequence of their wickedness that Jehovah is dispossessing them from before thee."

Verses 4, 5. - Speak not thou in thine heart (cf. Deuteronomy 8:17). The distinction between righteousness and uprightness (straightness) of heart, is that the former (צֶדֶ) has reference to rectitude of conduct, the latter (ישֶׁר) to rectitude of motive and purpose. "By naming justice [righteousness], he excludeth all merit of works, and by righteousness [uprightness] of heart, all inward affections and purposes. which men might plead, notwithstanding that they fail in action. Yet these two are the chief things which God respecteth in men (Psalm 15:1, 2; 1 Chronicles 29:17)" (Ainsworth).

9:1-6 Moses represents the strength of the enemies they were now to encounter. This was to drive them to God, and engage their hope in him. He assures them of victory, by the presence of God with them. He cautions them not to have the least thought of their own righteousness, as if that procured this favour at God's hand. In Christ we have both righteousness and strength; in Him we must glory, not in ourselves, nor in any sufficiency of our own. It is for the wickedness of these nations that God drives them out. All whom God rejects, are rejected for their own wickedness; but none whom he accepts are accepted for their own righteousness. Thus boasting is for ever done away: see Eph 2:9,11,12.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.