Commentaries:
Robertson's Word Pictures (NT)
Being fully assured (plhroforhqeiv). First aorist passive participle of plhroforew, from plhroforov and this from plhrhv and ferw, to bear or bring full (full measure), to settle fully. Late word, first in LXX but frequent in papyri in sense of finishing off or paying off. See on Luke 1:1; Romans 14:5.
What he had promised (o ephggeltai). Perfect middle indicative of epaggellomai, to promise, retained in indirect discourse according to usual Greek idiom.
He was able (dunatov estin). Present active indicative retained in indirect discourse. The verbal adjective dunatov with estin is here used in sense of the verb dunatai (Luke 14:31; Acts 11:17).
Other Robertson's Word Pictures (NT) entries containing Romans 4:21:
Luke 1:1
Romans 11:23
Romans 14:5
Titus 1:9
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