Genesis 15:12-14

"And when the sun was going down, a deep sleep fell upon Abram; and, lo, a horror of great darkness fell upon him. And he said unto Abram, Know of a surety that thy seed shall be sojourners in a land that is not theirs, and shall serve them; and they shall afflict them four hundred years; and also that nation, whom they shall serve, will I judge: and afterward shall they come out with great substance."

"And when the sun was going down ..." All of this is still part of the vision "The horror of a great darkness" was also part of it, as were the words spoken by Jehovah.

"They shall be sojourners ..." This is a prophetic revelation of the captivity of Israel in Egypt, "thy seed" being a reference to the posterity of Abram.

"Four hundred years ..." The same period is referred to as 430 years in Exodus 12:40, a well-known pseudocon, but no contradiction exists. Note that it is not the total stay in Egypt, but the period of their "affliction" which is here prophesied as "four hundred years." They were not afflicted during the early years of their sojourn there while Joseph was yet Pharaoh's deputy. Also, in all probability, the time period here is stated in round numbers, meaning "about four hundred years." The same period is called "four generations" a little later, that being correct in view of the longevity of the patriarchs.

"That nation will I judge ..." The ten plagues brought against Egypt, as fully related in Exodus, were the fulfillment of this.

"Come out with great substance ..." This too was related in Exodus. From Egyptians, the Israelites borrowed great wealth on the very night that God delivered them; and this immense booty they took with them into the wilderness. In these dire promises concerning Abram's seed there would seem to be the source of that "horror of great darkness" that came upon Abram.

This kind of prophecy was not intended to inspire shouts of joy on Abram's part.