NOTES for Gen 16:1-16
Time passes, and the promise on which Abram's whole life is now founded still has not been fulfilled. Clearly, God is waiting for some decisive step from him; it is time to act. And he acts: a son born of a slave woman is legally considered his heir and Sarah's son. The Lord allows and accepts his move; Ishmael too will be a famous man and a great father of nations. But the promise is not fulfilled by human moves and stratagems. It is God's work, and God must fulfill it by His own methods. Therefore God was waiting from Abram not so much for decisive actions as for decisive faith: the ability to allow that the impossible is possible and attainable if it is God's work, for that is exactly how all the most important events of human life take place...