John Calvin Commentary Joshua 1:4

"From the wilderness, and this Lebanon, even unto the great river, the river Euphrates, all the land of the Hittites, and unto the great sea toward the going down of the sun, shall be your border." — Joshua 1:4 (ASV)

From the wilderness and this Lebanon, etc. How the truth and fulfillment of this promise overcame all the obstacles created by the wickedness of the people, even though they did not obtain immediate possession of the whole territory, I have explained in the Argument. For although God had unfolded the inestimable treasures of his beneficence by making them lords of the country, it did not follow that their misconduct was not to be disciplined. Indeed, there needed to be a fulfillment of the threat which Moses had declared, namely, that if the nations doomed to destruction were not destroyed, they would prove thorns and stings in their eyes and sides. But just as the promise was by no means broken or invalidated by the delay of forty years, during which they were led wandering through the desert, so the entire possession, though long suspended, proved the faithfulness of the decree by which it had been ordained.

The people had it in their power to obtain possession of the prescribed boundaries at the proper time; they declined to do so. For this, they deserved to have been expelled altogether. Yet divine indulgence granted them an extent of territory sufficient for their suitable habitation.

And although it had been foretold that, as a just punishment, the remnant of the nations whom they spared would prove harmful to them, still, they suffered no trouble unless they provoked divine anger by their faithlessness and almost continual falling away; for as often as their affairs became prosperous, they turned aside to wantonness. Nevertheless, owing to the wonderful goodness of God, when oppressed by the violence of the enemy and, as it were, pushed down to the grave, they continued to live in death. Not only that, but from time to time deliverers arose and, contrary to all hope, rescued them from ruin.

The Great Sea means the Mediterranean, and to it the land of the Hittites forms the opposite boundary. In the same way, Lebanon is opposed to the Euphrates. However, it must be observed that under Lebanon the desert is included, as is evident from another passage.