Genesis 15:12

And when the sun was going down— The original is, and the sun was (לבוא labo, ad intrandum, says Montanus) about to enter, "the time of sun-rising approached," which I take to be the true sense of the passage. For, as I conceive, God came to Abram in the night, perhaps the beginning of it; after which he brought him forth, and ordered him to count the stars, if possible, Genesis 15:5. This done, he employs him in preparing this sacrifice; by which time morning drew near, "the sun was about to enter:" when Abram, fatigued with the business in which he had been employed, and wanting rest, fell into a deep sleep: then, as the sacred writer expresses it, an horror of great darkness fell upon him, or was represented in vision to him; the meaning of which is fully and clearly explained in the next verse.