For your eyes have seen all the great work of the LORD that he did.
Because God has made thee as the stars of heaven for multitude (so the preceding chapter concludes), therefore thou shalt love the Lord thy God (so this begins). Those whom God has built up into families, whose beginning was small, but whose latter end greatly increases, should use that as an argument with themselves why they should serve God.
Commenting on Deuteronomy 11:1-7
And that ye may prolong your days in the land,.... Not only enter it, and take possession of it, but continue in it long, which depended upon their obedience to the laws of God: which the Lord sware unto your fathers to give unto them and to their seed; had promised with an oath, so that they might be assured of the enjoyment of it...