Genesis 15:4-8

4Then behold, the word of Adonai came to him saying, “This one will not be your heir, but in fact, one who will come from your own body will be your heir.

5He took him outside and said, “Look up now, at the sky, and count the stars—if you are able to count them.” Then He said to him, “So shall your seed be.”

6Then he believed in Adonai and He reckoned it to him as righteousness.

7Then He said to him, “I am Adonai who brought you out from Ur of the Chaldeans, in order to give you this land to inherit it.”

8So he said, “My Lord Adonai, how will I know that I will inherit it?”