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 De toutes les bonnes paroles que l'Eternel avait dites à la maison d'Israël, aucune ne resta sans effet: toutes s'accomplirent.