Charles Spurgeon Commentary Romans 4:16-22

"For this cause [it is] of faith, that [it may be] according to grace; to the end that the promise may be sure to all the seed; not to that only which is of the law, but to that also which is of the faith of Abraham, who is the father of us all (as it is written, A father of many nations have I made thee) before him whom he believed, [even] God, who giveth life to the dead, and calleth the things that are not, as though they were. Who in hope believed against hope, to the end that he might become a father of many nations, according to that which had been spoken, So shall thy seed be. And without being weakened in faith he considered his own body now as good as dead (he being about a hundred years old), and the deadness of Sarah`s womb; yet, looking unto the promise of God, he wavered not through unbelief, but waxed strong through faith, giving glory to God, and being fully assured that what he had promised, he was able also to perform. Wherefore also it was reckoned unto him for righteousness." — Romans 4:16-22 (ASV)

Not to that only which is of the law, but to that also which is of the faith of Abraham; who is the father of us all, (as it is written, I have made thee a father of many nations,) before him whom he believed, even God, who quickeneth the dead, and calleth those things which be not as though they were. Who against hope believed in hope, that he might become the father of many nations, according to that which was spoken, So shall thy seed be. 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 4:16–21).

And therefore it was imputed to him for righteousness (Romans 4:22).

O soul, if you are like one who is dead, if you are devoid of all strength, grace, and spiritual life, if you can but believe in God who can quicken the dead, if you will but trust your soul in the hands of Him who is able even to raise dry bones out of their graves and make them live, your faith shall be imputed to you for righteousness! Your faith is that which shall justify you in the sight of God, and you shall be accepted in the Beloved (Ephesians 1:6). Oh, what marvels faith works!

This is the root-grace; all manner of good things spring from faith, but there must be faith as the root if there are to be other graces as the fruit. Do your God the honor to believe Him: to believe that He cannot lie, to believe that He has never promised what He is not able to perform. If you will do that, it is clear that you are one of Abraham's seed, and the covenant made with Abraham was made with you also.