Romans 4:21

English Standard Version

21 fully convinced that God was able to do what he had promised. (Ge 18:14; Heb 11:19)

New International Version

21 being fully persuaded that God had power to do what he had promised.

New Int. Readers Version

21 He was absolutely sure that God had the power to do what he had promised.

King James Version

21 And being fully persuaded that, what he had promised, he was able also to perform.