Thou shalt know also that thy seed [shall be] great
Not his seed sown in the earth, and the increase of that, but his children, as the next clause explains it, as Bar Tzemach well observes; and designs either their greatness in worldly things, in wealth and riches, in honour and dignity, in power and authority, or else their numbers; for the word may be rendered "much" or "many" F14, a multitude of children being reckoned a great temporal blessing; but this seems rather intended in the following words:
and thine offspring as the grass of the earth;
as numerous as the spires of grass, which can no more be told than the stars of the heavens, or the sand of the sea, by which the same thing, a numerous progeny, is sometimes illustrated: this is to be understood not of his immediate offspring, but his descendants in successive ages and generations, and which should be as beautiful as the grass of the earth when in its verdure; pointing at the comeliness of their persons, their honour and dignity raised unto, the largeness of their substance, the greatness of their prosperity, and flourishing circumstances they should be in; though it may also denote the original of them, amidst all, being of the earth and earthy, and their frailty and fading condition; for which reason all flesh is said to be as grass, and men are frequently compared unto it, see ( Psalms 90:5 Psalms 90:6 ) ( 102:4 ) ( 103:15 ) ( Isaiah 40:6-8 ) .