Genesis 15:2-5

2But Abram said, “O sovereign Lord, what will you give me since I continue to be childless, and my heir is Eliezer of Damascus?”

3Abram added, “Since you have not given me a descendant, then look, one born in my house will be my heir!”

4But look, the word of the Lord came to him: “This man will not be your heir, but instead a son who comes from your own body will be your heir.”

5The Lord took him outside and said, “Gaze into the sky and count the stars – if you are able to count them!” Then he said to him, “So will your descendants be.”