What does Genesis 21:2 mean?
God's timing is perfect. He had said within the hearing of both Abraham and Sarah that they would have a child within a year from a specific moment (Genesis 18:14). Though Abraham and Sarah had attempted to scheme a way to gain a son through another woman (Genesis 16:1–2), God specifically meant to provide them with their own natural child (Genesis 17:15–16). Despite their disbelieving laughter (Genesis 17:17; Genesis 18:12), that's exactly what happened. Not only does God keep His promises, He keeps them specifically.Sarah bears a son to Abraham in his old age. Saying these two are in their "old age," in this situation, is quite an understatement. The following verses will reveal that Abraham is 100 years old, meaning that Sarah is right around 90. It's never too late for God to keep His word. This makes Isaac's birth miraculous, not only because Sarah had been barren her entire life, but also because of her advanced age when she conceived.