Warning against a conceit of righteousness, with the occasion for the warning. As the Israelites were now about to cross over the Jordan (“this day,” to indicate that the time was close at hand), to take possession of nations that were superior to them in size and strength (the tribes of Canaan mentioned in Deu 7:1), and great fortified cities reaching to the heavens (cf. Deu 1:28), namely, the great and tall nation of the Enakites (Deu 1:28), before which, as was well known, no one could stand (הִתְיצֵּב, as in Deu 7:24); and as they also knew that Jehovah their God was going before them to destroy and humble these nations, they were not to say in their heart, when this was done, For my righteousness Jehovah hath brought me in to possess this land. In Deu 9:3, הַיֹּום וְיָדַעְתָּ is not to be taken in an imperative sense, but as expressive of the actual fact, and corresponding to Deu 9:1, “thou art to pass.” Israel now knew for certain - namely, by the fact, which spoke so powerfully, of its having been successful against foes which it could never have conquered by itself, especially against Sihon and Og - that the Lord was going before it, as the leader and captain of His people (Schultz: see Deu 1:30). The threefold repetition of הוּא in Deu 9:3 is peculiarly emphatic. “A consuming fire:” as in Deu 4:24. יַשְׁמִידֵם הוּא is more particularly defined by וגו יַכְנִיעֵם וְהוּא, which follows: not, however, as implying that הִשְׁמִיד does not signify complete destruction in this passage, but rather as explaining how the destruction would take place. Jehovah would destroy the Canaanites, by bring them down, humbling them before Israel, so that they would be able to drive them out and destroy them quickly “מַהֵר, quickly, is no more opposed to Deu 7:22, 'thou mayest not destroy them quickly,' than God's not delaying to requite (Deu 7:10) is opposed to His long-suffering” (Schultz). So far as the almighty assistance of God was concerned, the Israelites would quickly overthrow the Canaanites; but for the sake of the well-being of Israel, the destruction would only take place by degrees. “As Jehovah hath said unto thee:” viz., Exo 23:23, Exo 23:27., and at the beginning of the conflict, Deu 2:24.
When therefore Jehovah thrust out these nations before them (הָדַף, as in Deu 6:19), the Israelites were not to say within themselves, “By (for, on account of) my righteousness Jehovah hath brought me (led me hither) to possess this land.” The following word, וּבְרִשְׁעַת, is adversative: “but because of the wickedness of these nations,” etc. - To impress this truth deeply upon the people, Moses repeats the thought once more in Deu 9:5. At the same time he mentions, in addition to righteousness, straightness or uprightness of heart, to indicate briefly that outward works do not constitute true righteousness, but that an upright state of heart is indispensable, and then enters more fully into the positive reasons. The wickedness of the Canaanites was no doubt a sufficient reason for destroying them, but not for giving their land to the people of Israel, since they could lay no claim to it on account of their own righteousness. The reason for giving Canaan to the Israelites was simply the promise of God, the word which the Lord had spoken to the patriarchs on oath (cf. Deu 7:8), and therefore nothing but the free grace of God, - not any merit on the part of the Israelites who were then living, for they were a people “of a hard neck,” i.e., a stubborn, untractable generation. With these words, which the Lord Himself had applied to Israel in Exo 32:9; Exo 33:3, Exo 33:5, Moses prepares the way for passing to the reasons for his warning against self-righteous pride, namely, the grievous sins of the Israelites against the Lord.