Genesis 15:5-8

5And he brought him outside and said, "Look toward heaven, and number the stars, if you are able to number them." Then he said to him, "So shall your offspring be."

6And he believed the Lord, and he counted it to him as righteousness.

7And he said to him, "I am the Lord who brought you out from Ur of the Chaldeans to give you this land to possess."

8But he said, "O Lord God, how am I to know that I shall possess it?"