15:17-21 The smoking furnace and the burning lamp, probably represented the Israelites' severe trials and joyful deliverance, with their gracious supports in the mean time. It is probable that this furnace and lamp, which passed between the pieces, burned and consumed them, and so completed the sacrifice, and testified God's acceptance of it. So it intimates that God's covenants with man are made by sacrifice, Ps 50:5. And we may know that he accepts our sacrifices, if he kindles in our souls pious and devout affections. The bounds of the land granted are stated. Several nations, or tribes, are spoken of, that must be cast out to make room for the seed of Abram. In this chapter we perceive in Abram faith struggling against, and triumphing over, unbelief. Wonder not, believers, if you meet with seasons of darkness and distress. But it is not the will of God that you should be cast down: fear not; for all that he was to Abram he will be to you.

9-21. Take me an heifer, &c.—On occasions of great importance, when two or more parties join in a compact, they either observe precisely the same rites as Abram did, or, where they do not, they invoke the lamp as their witness. According to these ideas, which have been from time immemorial engraven on the minds of Eastern people, the Lord Himself condescended to enter into covenant with Abram. The patriarch did not pass between the sacrifice and the reason was that in this transaction he was bound to nothing. He asked a sign, and God was pleased to give him a sign, by which, according to Eastern ideas, He bound Himself. In like manner God has entered into covenant with us; and in the glory of the only-begotten Son, who passed through between God and us, all who believe have, like Abram, a sign or pledge in the gift of the Spirit, whereby they may know that they shall inherit the heavenly Canaan.