Romans 4:18-20

There was no hope that Abraham would have children. But Abraham believed God and continued hoping, and so he became the father of many nations. As God told him, “Your descendants also will be too many to count.” Abraham was almost a hundred years old, much past the age for having children, and Sarah could not have children. Abraham thought about all this, but his faith in God did not become weak. He never doubted that God would keep his promise, and he never stopped believing. He grew stronger in his faith and gave praise to God.