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 Ex 12:14,21:6, De 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.

Matthew Henry's Concise Commentary

13:14-18 Those are best prepared for the visits of Divine grace, whose spirits are calm, and not ruffled with passion. God will abundantly make up in spiritual peace, what we lose for preserving neighbourly peace. When our relations are separated from us, yet God is not. Observe also the promises with which God now comforted and enriched Abram. Of two things he assures him; a good land, and a numerous issue to enjoy it. The prospects seen by faith are more rich and beautiful than those we see around us. God bade him walk through the land, not to think of fixing in it, but expect to be always unsettled, and walking through it to a better Canaan. He built an altar, in token of his thankfulness to God. When God meets us with gracious promises, he expects that we should attend him with humble praises. In outward difficulties, it is very profitable for the true believer to mediate on the glorious inheritance which the Lord has for him at the last.