A.T. Robertson Commentary Romans 4:18

"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." — Romans 4:18 (ASV)

In hope believed against hope (παρ' ελπιδα επ' ελπιδ επιστευσεν). "Past hope in (upon) hope he trusted." Graphic picture.

To the end that he might become (εις το γενεσθα αυτον). Purpose clause again with εις to and the infinitive as in verses 11-16.