Faith

Without weakening in his faith, he faced the fact that his body was as good as dead—since he was about a hundred years old—and that Sarah's womb was also dead. Yet he did not waver through unbelief regarding the promise of God, but was strengthened in his faith and gave glory to God, being fully persuaded that God had power to do what he had promised. This is why "it was credited to him as righteousness." The words "it was credited to him" were written not for him alone, but also for us, to whom God will credit righteousness—for us who believe in him who raised Jesus our Lord from the dead. He was delivered over to death for our sins and was raised to life for our justification. (‭Romans‬ ‭4‬:‭19-25‬ NIV)