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.
and the Canaanites; which were a particular tribe or nation that bore the name of their great ancestor Canaan, see Genesis 13:7,
and the Girgashites; the same with the Gergesenes in Matthew 8:28; of these see Genesis 10:16,
and the Jebusites; who inhabited Jerusalem and about it, which was first called Jebus, from the founder of this nation; see Gill on Genesis 10:16.