Genesis 15

12 Now when the sun was going down, a deep sleep fell upon Abram; and behold, terror and great darkness fell upon him. 13 God said to Abram, “Know for certain that your descendants will be strangers in a land that is not theirs, where they will be enslaved and oppressed four hundred years. 14 “But I will also judge the nation whom they will serve, and afterward they will come out with many possessions. 15 “As for you, you shall go to your fathers in peace; you will be buried at a good old age. 16 “Then in the fourth generation they will return here, for the iniquity of the Amorite is not yet complete.”

Then in the fourth generation they will return here

Mahx Note:

It is this statement that ultimately answers Abraham's question, "How can I know that I will inherit the land?" The covenant made here is all about answering this question. God says to Abraham, in effect, you will know only when you are on the other side of death together with your ancestors. For it will be in a later generation that the actions that I perform to make Israel worthy of inheriting the Land will be done. Here it is said that they will be done in the fourth generation. God will make them worthy to return to the Land. But there will be an interruption in the process. Just as the mention of Abraham's death interrupts the narrative of the covenant, so there will be an interruption in the process of the coming up out of Egypt and the entering into the Land. First they will come up out of Egypt and with great possessions. This is one thing that is guaranteed. Then another thing that is guaranteed is that in the fourth generation they will return to the Land. And this is what happened. But even when they did enter the Land they did not enter the Land fully and dwell in the Land in faith fully in fulfillment of the covenant. To see this clearly we need to see clearly that the covenant was a covenant of all the promises that God made to Abraham.

On the largest scale there are three different promises. There is the promise of corporate blessing. There is the promise of an offspring. And there is the promise of the Land. Because the promise of the Land was made by God to represent to Abraham the other two promises, as well, when Abraham asked how he could know he would inherit the Land he was asking how he could know that all three promises would be fulfilled, and that they would not be lost through sins and rebellions. Therefore also, we can learn that so long as Israel has not received the Land from the hand of God in the same way that Israel received the power to leave Egypt and go to Sinai and receive the Torah, it has not fully received the fulfillment of the other promises.