Against hope (ἐλπίδα, a form of ἐλπίς) Abraham believed (ἐπίστευσεν, a form of πιστεύω) in hope (ἐλπίδι, another form of ἐλπίς),¹ Paul continued.  At ninety-nine-years old Abraham had plenty of empirical proof that his wife Sarah could not have a child.  He had no reason to hope in any natural sense of the word (i.e., against hope).  But Paul had this to say about hope in the next chapter (Romans 5:3, 4 NET):

Not only this, but we also rejoice in sufferings, knowing that suffering produces endurance (ὑπομονὴν, a form of ὑπομονή), and endurance (ὑπομονὴ), character, and character, hope (ἐλπίδα, a form of ἐλπίς).  And hope (ἐλπὶς) does not disappoint, because the love (ἀγάπη) of God has been poured out in our hearts through the Holy Spirit who was given to us.

Now suffering in and of itself does not necessarily produce endurance in a person, and endurance in and of itself does not necessarily produce godly character.  The reason suffering produces endurance and endurance, godly character and godly character, hope is God’s love poured out in the heart of a man or woman.  This is the love that bears all things, believes (πιστεύει, another form of πιστεύω) all things, hopes (ἐλπίζει, a form of ἐλπίζω) all things, endures (ὑπομένει, a form of ὑπομένω) all things.²  And so Abraham believed in God in hope, rather than believing in hope itself.  This is clearer in verse 21, He was fully convinced that what God promised (ἐπήγγελται, a form of ἐπαγγέλλω) he was also able to do (ποιῆσαι, a form of ποιέω).³

The result for Abraham of believing God in hope against hope was that he became the father of many nations according to the pronouncement, “so will your descendants be.”⁴  What follows is a special revelation: Without being weak in faith (πίστει, a form of πίστις), he considered his own body as dead (because he was about one hundred years old) and the deadness of Sarah’s womb [Table].  He did not waver in unbelief (ἀπιστία) about the promise (ἐπαγγελίαν, a form of ἐπαγγελία) of God but was strengthened (ἐνεδυναμώθη, a form of ἐνδυναμόω) in faith (πίστει, a form of πίστις), giving glory to God.⁵

From the time God confirmed that Abraham would have a son by Sarah in Genesis 17:19-22 until Isaac was born in Genesis 21:1-5 there is nothing in the narrative that helps me see that this faith Paul revealed in Romans 4:19 and 20 was working together with Abraham’s works.⁶  In fact, I’m not even able to imagine what works Abraham could have done to indicate that he was fully convinced that what God promised he was also able to do⁷ in reference to Sarah having a son.

This particular aspect of Abraham’s faith is a good object lesson for Paul’s declaration to the Corinthians: So then, do not judge anything before the time.  Wait until the Lord comes.  He will bring to light the hidden things of darkness and reveal the motives of hearts.  Then each will receive recognition from God.⁸  Apart from the Lord’s revelation of Abraham’s heart through Paul I would not know this particular aspect of Abraham’s faith from reading Genesis alone.  There is, however, a story where I can see the outworking of Abraham’s credited righteousness, and his faith working together with his works, as James highlighted in his letter.⁹  In the letter to the Hebrews more of Abraham’s heart was revealed (Hebrews 11:17-19 NET).

By faith (Πίστει, a form of πίστις) Abraham, when he was tested (πειραζόμενος, a form of πειράζω), offered up Isaac.  He had received the promises (ἐπαγγελίας, another form of ἐπαγγελία), yet he was ready to offer up his only son.  God had told him, “Through Isaac descendants will carry on your name,” and he reasoned (λογισάμενος, a form of λογίζομαι) that God could even raise him from the dead, and in a sense he received him back from there.

God said to Abraham, Take your son – your only son, whom you love, Isaac – and go to the land of Moriah!  Offer him up there as a burnt offering on one of the mountains which I will indicate to you.¹⁰  The first work I see working together with Abraham’s revealed faith that God could even raise Isaac from the dead is more Zen than Hebrew, a not-work, if you will.  There are no George C. Scott histrionics from the John Huston film The Bible, an aesthetic choice presumably to make Abraham more believable to unbelievers.  Early in the morning Abraham got up and saddled his donkey.  He took two of his young servants with him, along with his son Isaac.  When he had cut the wood for the burnt offering, he started out for the place God had spoken to him about.¹¹

The next work I see working together with Abraham’s revealed faith that God could even raise Isaac from the dead is Abraham’s answer to Isaac’s question, where is the lamb?  “God will provide for himself the lamb for the burnt offering, my son,” Abraham replied.  The two of them continued on together.¹²  And the final work is that mentioned by James (Genesis 22:9, 10 NET):

When they came to the place God had told him about, Abraham built the altar there and arranged the wood on it.  Next he tied up his son Isaac and placed him on the altar on top of the wood.  Then Abraham reached out his hand, took the knife, and prepared to slaughter his son.

But the Lord’s angel called to him from heaven…“Do not harm the boy!…Do not do anything to him, for now I know that you fear God because you did not withhold your son, your only son, from me.¹³  Then Abraham’s prophetic word to Isaac was fulfilled.  Abraham looked up and saw behind him a ram caught in the bushes by its horns.  So he went over and got the ram and offered it up as a burnt offering instead of his son.¹⁴

Abraham was fully convinced that what God promised (ἐπήγγελται, a form of ἐπαγγέλλω) he was also able to do (ποιῆσαι, a form of ποιέω), Paul wrote the Romans.  So indeed it was credited (ἐλογίσθη, another form of λογίζομαι) to Abraham as righteousness (δικαιοσύνην, a form of δικαιοσύνη).¹⁵  Paul’s interest was not merely historical, the statement it was credited (ἐλογίσθη, another form of λογίζομαι) to him was not written only for Abraham’s sake, but also for our sake, to whom it will be credited (λογίζεσθαι, another form of λογίζομαι), those who believe in the one who raised Jesus our Lord from the dead.  He was given over (παρεδόθη, a form of παραδίδωμι) because of our transgressions (παραπτώματα, a form of παράπτωμα) and was raised for the sake of our justification (δικαίωσιν, a form of δικαίωσις).¹⁶

I think it is important to remember who Paul referred to when he said our sake, our transgressions and our justification.  …it is by faith (πίστεως, another form of πίστις) so that it may be by grace (χάριν, a form of χάρις), with the result that the promise (ἐπαγγελίαν, a form of ἐπαγγελία) may be certain to all the descendants – not only to those who are under the law (νόμου, a form of νόμος), but also to those who have the faith (πίστεως, another form of πίστις) of Abraham, who is the father of us all…¹⁷

Addendum: February 29, 2024
According to a note (33) in the NET Paul quoted from Genesis 17:5 in Romans 4:18a. A table comparing the Greek of Paul’s quotation with that of the Septuagint follows.

According to a note (35) in the NET Paul quoted from Genesis 15:5 in Romans 4:18b. A table comparing the Greek of Paul’s quotation with that of the Septuagint follows.

According to a note (22) in the NET the author of Hebrews quoted from Genesis 21:12 in Hebrews 11:18b. A table comparing the Greek of that quotation with that of the Septuagint follows.

According to a note (42) in the NET Paul quoted from Genesis 15:6 in Romans 4:23. A table comparing the Greek of Paul’s quotation with that of the Septuagint follows.

Tables comparing Genesis 22:3; 22:8; 22:11; 22:12 and 22:13 in the Tanakh, KJV and NET, and tables comparing the Greek of Genesis 22:3; 22:8; 22:11; 22:12 and 22:13 in the Septuagint (BLB and Elpenor) follow.