Genesis 15:3-7

Abram also said, “Since You have given me no son, one who has been born in my house is my heir.”

Then behold, the word of the Lord came to him, saying, “This man will not be your heir; but one who will come from your own body shall be your heir.”

And He took him outside and said, “Now look toward the heavens and count the stars, if you are able to count them.” And He said to him, “So shall your descendants be.”

Then he believed in the Lord; and He credited it to him as righteousness.

And He said to him, “I am the Lord who brought you out of Ur of the Chaldeans, to give you this land to possess it.”