And being not weak in faith, he considered not his own body now dead, when he was about an hundred years old; neither yet the deadness of Sarah's womb.
He staggered not at the promise of God through unbelief; but was strong in faith, giving glory to God;
And being fully persuaded that, what he had promised, he was able also to perform. Romans 4:19-21
But heck, Abraham, when he was even older, managed to father six more children with a new wife without any divine assistance (Gen 25:1-2)