The defeat of Israel would be due to the fact that God, their strength, had abandoned them because of their apostasy.

How should one chase a thousand - If therefore they had not forgotten their Rock, God their author and defense, it could not possibly have come to pass that a thousand of them should flee before one of their enemies.

Deuteronomy 32:30."And five of you shall chase a hundred;

And a hundred of you shall chase (רבבה) ten thousand."

How should one chase a thousand, and two put ten thousand to flight,.... This is said for the conviction of the Pagan Romans of their folly in behaving strangely, attributing to their gods what belonged to the true God; for since the Jews were more numerous than they, both in Judea, in the times of Titus Vespasian, when the country was subdued by him; and in other parts of the world, in the times of Adrian, when the Jews rose up in vast numbers, greatly superior to the Romans, and yet were conquered; which, allowing the phrase to be hyperbolical, was like one to a thousand, and two to ten thousand: now since this was what was promised to the Jews in case of obedience, that they should in this manner chase their enemies, Leviticus 26:8; it cannot be accounted for that they should in like manner be chased by their enemies, as threatened Isaiah 30:17,

except their rock had sold them, and the Lord had shut them up; that is, unless the Lord, who was their rock and fortress, and in whom they should have trusted as such, had forsaken them, and given them up into their enemies' hands, shut up as they were in the city of Jerusalem in the times of Titus, and afterwards in Bither in the times of Adrian; it is a plain case that this was of God, and not owing to the idols of the Gentiles; see Psalm 44:9; Cocceius and Van Till interpret this of Constantine overcoming Maxentius, Licinius, and Maximinius, whereby the whole Roman empire on a sudden became Christian nominally, when but a little before Dioclesian had erected a trophy with this inscription on it,"the Christian name blotted out;''so that the odds between the Christians and Pagans were as one to a thousand, and two to ten thousand, and the victory therefore must be ascribed to God; this could never have been unless Satan, the great red dragon, had given his kingdom to the beast, which was done by the permission and sovereign will of God; see Revelation 6:14; so those interpreters, but the former sense seems best.

If Israel were wise, it could easily conquer all its foes in the power of its God (vid., Leviticus 26:8); but as it had forsaken the Lord its rock, He, their (Israel's) rock, had given them up into the power of the foe. כּי לא אם is more emphatic or distinct than לא אם only, and introduces an exception which does not permit the desired event to take place. Israel could have put all its enemies to flight were it not that its God had given it entirely up to them (sold them as slaves). The supposition that this had already occurred by no means proves, as Kamphausen believes, "that the poet was speaking of the existing state of the nation," but merely that Moses thinks of the circumstances as certain to occur when the people should have forsaken their God. The past implied in the verbs "sold" and "given up" is a prophetically idea past or present, but not a real and historical one. The assertion of Hupfeld and Kamphausen, that מכר, as used with special reference to the giving up of a nation into the power of the heathen, "belongs to a somewhat later usage of the language," is equally groundless.

How should one chase a thousand, and two put ten thousand to flight, except their Rock had sold them, and the LORD had shut them up?

32:30 One - Israelite. Their rock - Their God, who was their refuge and defence. Sold them - Namely, for bond - slaves, had given themselves up into their enemies hands. Shut them up - As it were in the net which their enemies had laid for them.

32:26-38 The idolatry and rebellions of Israel deserved, and the justice of God seemed to demand, that they should be rooted out. But He spared Israel, and continues them still to be living witnesses of the truth of the Bible, and to silence unbelievers. They are preserved for wise and holy purposes and the prophecies give us some idea what those purposes are. The Lord will never disgrace the throne of his glory. It is great wisdom, and will help much to the return of sinners to God, seriously to consider their latter end, or the future state. It is here meant particularly of what God foretold by Moses, about this people in the latter days; but it may be applied generally. Oh that men would consider the happiness they will lose, and the misery they will certainly plunge into, if they go on in their trespasses! What will be in the end thereof? Jer 5:31. For the Lord will in due time bring down the enemies of the church, in displeasure against their wickedness. When sinners deem themselves most secure, they suddenly fall into destruction. And God's time to appear for the deliverance of his people, is when things are at the worst with them. But those who trust to any rock but God, will find it fail them when they most need it. The rejection of the Messiah by the Jewish nation, is the continuance of their ancient idolatry, apostacy, and rebellion. They shall be brought to humble themselves before the Lord, to repent of their sins, and to trust in their long-rejected Mediator for salvation. Then he will deliver them, and make their prosperity great.