Kabbalah sa Genesis 15:18: Zohar Chadash

“In the beginning (Bereishit), God created” (Genesis 1:1): Rabbi Abba began and said: “On that day. the Lord made a covenant with Avram, saying” (Genesis 15:18). The covenant was said about five things: The first is circumcision, as it is stated (Genesis 17:13), “this shall be My covenant in your flesh as an eternal covenant.” The second is the rainbow, as it is stated (Genesis 9:13), “and it shall be a sign of the covenant.” The third is the covenant of salt, as it is stated (Numbers 18:19), “an everlasting covenant of salt.” The fourth is the covenant of afflictions, as it is stated (Deuteronomy 28:69), “These are the words of the covenant.” The fifth is the covenant of the priesthood, as it is stated (Numbers 25:13), “And it shall be for him, and for his offspring after him, an everlasting covenant of priesthood.”

But before the five covenants were given, there was only the covenant with fire, as it is stated (Genesis 15:17), “and behold, a smoking furnace and a flaming torch, etc.” And it is written (Genesis 15:18), “On that day the Lord made a covenant with Avram, saying.” But the fire was a covenant at first. And this is [the meaning of] Bereishit - take out fire (esh) from there, and brit (covenant) remains. Meaning to say, brit esh (a covenant of fire).