NOTES for Gen 15:1-21
For the land promised by God to belong to Abram and his descendants, Abram must have an heir. But this is impossible, since his wife cannot have children, and both of them are no longer of childbearing age. Therefore, when God gives a new promise that Abram will have a son, he asks for proof: a miracle, a sign, something that would confirm such an extraordinary word. No miracle happens; God tells him to bring Him an offering. This means that He asks Abram to draw nearer to Him, to share a meal with Him, to become His friend. It is no accident that Scripture calls Abram, because of his trust in God, the friend of God (Jas 2:23). And a friend does not need proof; he believes another's word for the sake of friendship. In this way the promise of simple earthly things -- land, descendants, a son -- brings Abram into friendship with the Creator, into a union, a covenant, on which all subsequent history will be built.