To thee will I give it, and to thy seed for ever - This land was given to Abram, that it might lineally and legally descend to his posterity; and though Abram himself cannot be said to have possessed it, Acts 7:5, yet it was the gift of God to him in behalf of his seed; and this was always the design of God, not that Abram himself should possess it, but that his posterity should, till the manifestation of Christ in the flesh. And this is chiefly what is to be understood by the words for ever, אד עולם ad olam, to the end of the present dispensation, and the commencement of the new. עולם olam means either Eternity, which implies the termination of all time or duration, such as is measured by the celestial luminaries: or a hidden, unknown period, such as includes a completion or final termination of a particular era, dispensation, etc.; therefore the first is its proper meaning, the latter its accommodated meaning. See the note on Genesis 17:7. See the note on Genesis 21:33.

For all the land which thou seest, to thee will I give it, and to thy seed for (l) ever.
(l) Meaning a long time, and till the coming of Christ as in (Exodus 12:14, Exodus 21:6; Deuteronomy 15:17) and spiritually this refers to the true children of Abram born according to the promise, and not according to the flesh, which are heirs of the true land of Canaan.

For all the land which thou seest, to thee will I give it,.... Not only so much of it as his eye could reach, but all of it, as far as it went, which way soever he looked; and this he gave him to sojourn in now where he pleased, and for his posterity to dwell in hereafter; he gave him the title to it now, and to them the possession of it for future times:
and to thy seed for ever; the meaning is, that he gave it to his posterity to be enjoyed by them until the Messiah came, when a new world would begin; and which Abram in person shall enjoy, with all his spiritual seed, after the resurrection, when that part of the earth will be renewed, as the rest; and where particularly Christ will make his personal appearance and residence, the principal seed of Abram, and will reign a thousand years; see Gill on Matthew 22:32; besides, this may be typical of the heavenly Canaan given to Abram, and all his spiritual seed, and which shall be enjoyed by them for evermore.