Charles Spurgeon Commentary Genesis 15:7-8

"And he said unto him, I am Jehovah that brought thee out of Ur of the Chaldees, to give thee this land to inherit it. And he said, O Lord Jehovah, whereby shall I know that I shall inherit it?" — Genesis 15:7-8 (ASV)

What! Abraham, is not God's promise sufficient for you? O father of the faithful, though you do believe, and are counted as righteous through believing, do you still ask, "Whereby shall I know?" Ah, beloved! faith is often marred by a measure of unbelief; or, if not quite unbelief, yet there is a desire to have some token, some sign, beyond the bare promise of God.