Commentaries:
Robertson's Word Pictures (NT)
Feed him (ywmize auton). Quotation from LXX text of Proverbs 25:21 f. Present active imperative of verb from ywmov, a morsel, and so to feed crumbs to babies, then to feed in general. In N.T. only here and I Corinthians 13:3.
Thou shalt heap (swreuseiv). Future active of old verb swreuw from swrov, a heap. In N.T. only here and II Timothy 3:6.
Coals of fire (anqrakav purov). That is, burning or live coals.
Anthrax (our "anthracite") is an old word, only here in N.T. It is a metaphor for keen anguish. The Arabs have a proverb "coals in the heart," "fire in the liver." Such kindness may lead to repentance also.
Other Robertson's Word Pictures (NT) entries containing Romans 12:20:
Matthew 5:43
2 Timothy 3:6
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