“The Lord visited Sarah as he had said, and the Lord did to Sarah as he had promised” (v21). Sarah, who had not born children when she was young, gave birth in her old age. The gift of Isaac was “laughter” (v6); he symbolized grace and favor not just for her and Abraham, but ultimately for the whole world. God did not forget Abraham’s son Ishmael (he would become “a great nation” v18), yet Isaac was the miracle child of promise, foretaste of another promised Child to come.

“Through Isaac your offspring shall be named” (v12). Paul tells us that by faith in Christ we, like Isaac, are “children of promise” (Gal 4:28). When all hope was gone, God sent His Son to save us.