He took him outside and said, “Look up at the sky and count the stars—if indeed you can count them.” Then he said to him, “So shall your offspring be.” Abram believed the Lord, and he credited it to him as righteousness. He also said to him, “I am the Lord, who brought you out of Ur of the Chaldeans to give you this land to take possession of it…” Then the Lord said to him, “Know for certain that for four hundred years your descendants will be strangers in a country not their own and that they will be enslaved and mistreated there. But I will punish the nation they serve as slaves, and afterward they will come out with great possessions.
Genesis 15:57-,13-14