That is, live coals. See on Prov. 25:22. Kindness is the best vengeance that a Christian can take against an enemy. That heaping coals of fire on an opponent’s head must mean an act of love rather than of malice is clearly indicated by both the OT and NT contexts. The passage in Prov. 25:22 closes with these words, not quoted here by Paul, “and the Lord shall reward thee,” namely, for the good deeds done to your enemy. Similarly in the present context, the general meaning is summed up in the words, “Be not overcome of evil, but overcome evil with good” (Rom. 12:21).