As coals are to burning coals. As black, cold charcoal feeds glowing charcoal, as wood feeds a lighted fire, so a quarrelsome man (Proverbs 21:9; Proverbs 27:15) supports and nourishes strife. The verse is the counterpart of the preceding.
Septuagint, "A hearth for coal and logs for fire, and a reviling man for tumult of strife."