John Wesley on Joshua 23:4

That remain - Not yet conquered. An inheritance - You shall certainly subdue them, and inherit their hand, as you have done the rest, if you be not wanting to yourselves. All the nations - That is, with the land of those nations; the people put for their land, as we have seen before; and as sometimes on the contrary, the land is put for the people. The great sea - Where the Philistines, your most formidable adversaries yet survive; but them also and their land I have given to you, and you shall undoubtedly destroy them, if you will proceed vigorously in your work.