“Be strong, all you people of the land,” declares The Lord, “and work. For I am with you,” declares The Lord Almighty. “This is what I covenanted with you when you came out of Egypt. And My Spirit remains among you. Do not fear.”
Romans 4:20-25 NIV
Abraham 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.