When Abram was ninety-nine years old, the LORD appeared to him and said, “I am God Almighty. Walk before Me and be blameless. ... Abraham fell facedown. Then he laughed and said to himself, “Can a child be born to a man who is a hundred years old? Can Sarah give birth at the age of ninety?”
And he received the sign of circumcision as a seal of the righteousness that he had by faith while he was still uncircumcised. So then, he is the father of all who believe but are not circumcised, in order that righteousness might be credited to them. ... Without weakening in his faith, he acknowledged the decrepitness of his body (since he was about a hundred years old) and the lifelessness of Sarah’s womb. Yet he did not waver through disbelief in the promise of God, but was strengthened in his faith and gave glory to God,