John Calvin Commentary Joshua 21:43

"So Jehovah gave unto Israel all the land which he sware to give unto their fathers; and they possessed it, and dwelt therein." — Joshua 21:43 (ASV)

And the Lord gave to Israel, etc. Should anyone raise a question about this rest, the answer is easy. The nations of Canaan were so completely overcome with fear that they thought they could not better serve their interests than by servilely flattering the Israelites and purchasing peace from them on any terms. Plainly, therefore, the country was subdued and made peaceful for habitation, since no one caused any trouble, or dared to entertain any hostile intentions, since there were no threats, no snares, no violence, no conspiracies.

A second point, however, raises some doubt, namely, how the children of Israel can be said to have been settled in the possession of the land promised to them, and to have become masters of it, so that in regard to its enjoyment, not one syllable of God's promises had failed. For we have already seen that many of the enemy were intermingled with them. The divine intention was that not one of the enemy should be permitted to remain; on the other hand, the Israelites did not drive out many, but admitted them as neighbors, as if the inheritance had been common to them; they even made pacts with them. How then can these two things be reconciled: that God, as He had promised, gave the people possession of the land, and yet they were excluded from some portion by the power or obstinate resistance of the enemy?

In order to remove this appearance of contradiction, it is necessary to distinguish between the certain, clear, and steadfast faithfulness of God in keeping His promises, and the weakness and sluggishness of the people, as a consequence of which the benefit of divine goodness, in a way, slipped through their hands.

Whatever war the people undertook, in whatever direction they moved their standards, victory was prepared for them. Nor was there any other delay or obstacle to their exterminating all their enemies than their own voluntary lethargy. Therefore, although they did not defeat them all so as to secure their possession completely, yet the truth of God was clearly demonstrated and realized, since they could have obtained what remained without any difficulty, if they had chosen to take advantage of the victories offered to them.

The whole matter comes to this: it was entirely due to their own cowardice that they did not enjoy God's goodness in all its fullness and integrity. This will become even clearer from the following chapter.