Genesis 15:17
And it came to pass, that, when the sun went down, and it was dark, behold a smoking furnace, and a burning lamp that passed between those pieces. And it came to pass, that, when the sun went down, and it was dark, behold a smoking furnace, and a burning lamp that passed between those pieces.
After the sun had set and darkness came on, a smoke-filled furnace and a flaming lamp moved between the separated portions of the sacrificed animals, and these were emblems of the divine presence itself passing through the pathway and consuming the victims. That movement between the pieces was a solemn pledge ratifying the covenant made with Abraham and through him with humanity. The covenant thus ratified granted the land of Canaan to Abraham's descendants as their possession.
The furnace foreshadowed the oppression and affliction Israel would endure in Egypt, while the lamp foreshadowed divine intervention against their oppressors. Together they accompanied the promise that the enslaved people would be brought out with great substance. When Moses afterward scattered ashes from a furnace in Egypt, that act was a token to Israel that the covenant was remembered and that the hour of deliverance had arrived.
The same night vision reached beyond Egypt to the later sufferings of Abraham's descendants. It pointed forward to the death of Christ and to His return in glory. It pointed at last to the earth made new and restored to its Eden condition as Abraham's everlasting inheritance.