How old were Abraham and Sarah when the promises were fulfilled?
Abraham was 100 years old and Sarah was 90 when God performed the promise, and it became fulfilled. This came after nearly 50 years of waiting, beginning when Abraham was about 50 in Ur and not leaving Haran until he was 75.
Les teaches that God's promises to Abraham began in Ur when he was probably about 50. Abraham did not leave Haran until he was 75, and he did not receive Ishmael until he was near 80. Finally, when Abraham was 100 and Sarah was 90, God performed and the promises became fulfilled. Les points out that Abraham had almost 50 years to 'sweat the promises' with nothing happening, and he says he cannot blame Abraham for listening to Sarah and having a child by a slave girl, because God seemed inactive. But Les reminds us that God's wheels grind slowly but surely, and after 50 years of promises, the child came. This illustrates how easily faith can be crushed under circumstances, yet we must come back to Abraham and trust God's timing.