Genesis 15:4-8

15:4 But 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.” 15:5 The 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.”

15:6 Abram believed the Lord, and the Lord considered his response of faith as proof of genuine loyalty.

15:7 The Lord said to him, “I am the Lord who brought you out from Ur of the Chaldeans to give you this land to possess.” 15:8 But Abram said, “O sovereign Lord, by what can I know that I am to possess it?”