If thou shalt keep all these commandments to do them, which I command thee this day,.... A phrase often met with before, and signifies the putting in practice the several laws, moral, ceremonial, and judicial, which Moses was now making a repetition of, and enjoining the observance of them by a divine authority:
to love the Lord thy God; which is the source and spring of genuine obedience to the commands of God:
and to walk ever in his ways; noting constancy and perseverance in them; now all this is mentioned as the condition of the enlargement of their coast, which would be the case if a due and constant regard was had to the laws of God:
and then shall thou add three cities more besides these three; three more in the land of Canaan, besides the three now ordered to be separated in it, and besides the three on the other side of Jordan; so that there would have been nine in all, if these had been ever added; but that time never came: the Jews expect the addition of these three cities in the days of the Messiah y but the Messiah is already come, and all those cities, as they were typical of him, have had their accomplishment in him the antitype of them, of which
y Maimon. Hilchot Rotzeach, c. 8. sect. 4.