The author of Joshua is focusing particularly on the promise made by God to give Abraham descendants and a land. With this statement he is asserting that that promise has now come to completion. The people of Israel are living in the land; the promise has been kept. This faithfulness of the Lord is meant to provoke praise in his people—praise similar to what we find in Romans 11:33–36.1
45 Not one word of all the good promises that the LORD had made to the house of Israel had failed; all came to pass.