In Genesis 15:9-21 we find the story of God sealing his covenant with Abram (before he became Abraham) by means of animal sacrifices. In response to Abram’s request for a sign that God would fulfill his promise (vs. 8), God instructed him to take various animals and sacrifice them in a particular manner. After killing the animals, Abram divided them into halves, placing them on the ground in such a way that someone could walk between the halves of the carcasses. The narrative then states: “When the sun had set and darkness had fallen, a smoking firepot with a blazing torch appeared and passed between the pieces. On that day the Lord made a covenant with Abram …” (Genesis 15:17-18).
Many biblical commentaries suggest that this event was symbolic of such things as the “furnace of affliction” Israel would suffer in Egypt, but there is no reason to make such a symbolic connection, especially one so stretched. The real meaning of this event can be clearly seen from what is known of ancient Near Eastern land grant treaties (a type of “suzerain-vassal treaty” in which an agreement is made between two unequal parties, one of higher status and one of lower status, in which land is granted to the ruler of lower status on condition of faithfulness to the higher king). In this type of ritual, sacrificed animals were divided in half and in some cases the participants to the treaty walked between the halves of the animals as a way to seal the agreement made by the participants. This legal procedure of the world in which Abram lived is clearly central to understanding the story of Genesis 15. Perhaps Abram walked between the animal halves when he arranged them on the ground, but it is clear that God did – represented by the burning torch which "passed between the pieces."
Another, much later (c. 590 BC), but clearly parallel biblical example of this ritual in the time of Zedekiah involves an animal being killed, cut into two pieces, and then individuals passing between the divided pieces (Jeremiah 34:8–22 and note vss. 15, 19).
The Hebrew Bible speaks of covenants not as being “made” but as being “cut” (Hebrew karat ), and the ancient sacrificial covenant animal cutting practice explains that usage.