There failed not ought of any good thing which the LORD had spoken unto the house of Israel; all came to pass.

Wesley's Notes

21:45 All came to pass - Such an acknowledgment as this, here subscribed by Joshua, in the name of all Israel, we afterward find made by Solomon; and all Israel did in effect say amen to it, 1Kings 8:56. The inviolable truth of God's promise, and the performance of it to the uttermost, is what all believers in Christ have been always ready to bear their testimony to. And if in any thing it has seemed to come short, they have been as ready to take all the blame to themselves.

Matthew Henry's Concise Commentary

21:43-45 God promised to give to the seed of Abraham the land of Canaan for a possession, and now they possessed it, and dwelt therein. And the promise of the heavenly Canaan is as sure to all God's spiritual Israel; for it is the promise of Him that cannot lie. There stood not a man before them. The after-prevalence of the Canaanites was the effect of Israel's slothfulness, and the punishment of their sinful inclination to the idolatries and abominations of the heathen whom they harboured and indulged. There failed not aught of any good thing, which the Lord had spoken to the house of Israel. In due season all his promises will be accomplished; then will his people acknowledge that the Lord has exceeded their largest expectations, and made them more than conquerors, and brought them to their desired rest.