And when the sun was going down, a deep sleep fell upon Abram; and, lo, an horror of great darkness fell upon him. A deep sleep - תרדמה tardemah, the same word which is used to express the sleep into which Adam was cast, previous to the formation of Eve; Genesis 2:21.
A horror of great darkness - Which God designed to be expressive of the affliction and misery into which his posterity should be brought during the four hundred years of their bondage in Egypt; as the next verse particularly states.