“The theme of the Pentateuch is the partial fulfillment—which implies also the partial non-fulfillment—of the promise to or blessing of the patriarchs. The promise or blessing is both the divine initiative in a world where human initiatives always lead to disaster, and are an affirmation of the primal divine intentions for humanity.
The promise has three elements: posterity, divine-human relationship, and land. The posterity element of the promise is dominant in Genesis 12-50, the relationship element in Exodus and Leviticus, and the land element in Numbers and Deuteronomy.” (David J. A. Clines, The Theme of the Pentateuch, 2nd ed., p. 30)