Gen 17:8

“And I will give unto thee, and to thy seed after thee,.... To him in right, and to them in possession, and for an inheritance: the land wherein thou art a stranger; or "the land of sojournings" or "pilgrimages" (l), which were many; for he often removed from place to place, and sometimes sojourned in one place, and sometimes in another: all the land of Canaan, for an everlasting possession; this respects only the natural seed of Abraham, and those in the line of Isaac and Jacob, to whom this land was given to hold for ever, in case they were obedient to the will of God; and therefore whenever they were disobedient, they were carried captive from it, as they are at this day; but when they shall be converted, they will return to this land and possess it to the end of the world; and which was a figure of the heavenly inheritance, which is an eternal one, and will be enjoyed by all his spiritual seed to all eternity: and I will be their God; as he was to all the natural seed of Abraham in a spiritual sense, to whom the adoption belonged, and whom he chose and separated as a peculiar people to himself, and bestowed in providence many peculiar favours upon them, both in a civil and religious way; and as he is to all his spiritual seed in an evangelic sense, to whom he stands in the relation of their covenant God and Father in Christ, in whom he blesses them with all spiritual blessings, and will continue to be so unto death, and to all eternity. (l) "terram peregrinationum tuarum", Pagninus, Montanus, &c.”

“Everlasting possession - Here עולם olam appears to be used in its accommodated meaning, and signifies the completion of the Divine counsel in reference to a particular period or dispensation. And it is literally true that the Israelites possessed the land of Canaan till the Mosaic dispensation was terminated in the complete introduction of that of the Gospel. But as the spiritual and temporal covenants are both blended together, and the former was pointed out and typified by the latter, hence the word even here may be taken in its own proper meaning, that of ever-during, or eternal; because the spiritual blessings pointed out by the temporal covenant shall have no end. And hence it is immediately added, I will be their God, not for a time, certainly, but for ever and ever. See the note on Gen 21:33.”