Thou shalt know also that thy seed shall be multiplied, and thy offspring like the grass of the earth.

And thou shalt know that thy seed is numerous, and thine offspring as the herb of the earth.

And hast known that numerous is Thy seed, And thine offspring as the herb of the earth;

You will be certain that your seed will be great, and your offspring like the plants of the earth.

You shall know also that your descendants shall be great, and your offspring as the grass of the earth.

Likewise, you will know that your offspring will be manifold and your progeny will be like the grass of the earth.

Thou shalt know also that thy seed shall be great - Margin, "much." That is, thy posterity shall be numerous. This was one of the blessings supposed to be connected with the favor of God; see the notes at Isaiah 53:10.
And thine offspring as the grass of the earth - On the meaning of the word here rendered offspring, see the notes at Isaiah 48:19. Nothing is more common in the Scriptures, than to compare a prosperous and a happy man to a green and flourishing tree; see Psalm 1:3; Psalm 92:12-14. The idea here is, that the righteous would have a numerous and a happy posterity, and that the divine favor to them would bc shown by the blessing of God on their children; compare Psalm 128:1, Psalm 128:3.
Blessed is every one that feareth the Lord,
That walketh in his ways.
Thy wife shall be a fruitful vine by the side of thine house;
Thy children like olive-plants round about thy table.

Thine offspring as the grass - Thou shalt have a numerous and permanent issue.

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" (n), 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 Psalm 90:5.
(n) "multum", Pagninus, Montanus, Vatablus, Mercerus, Piscator, Schmidt, Michaelis.

as the grass-- (Psalm 72:16). Properly, "herb-bearing seed" (Genesis 1:11-12).

Know - By assurance from God's promises, and the impressions of his Spirit; and by experience in due time.