| Clarke's Commentary on the Bible Thou shalt heap coals of fire upon his head - Not to consume, but to melt him into kindness; a metaphor taken from smelting metallic ores: - So artists melt the sullen ore of lead, By heaping coals of fire upon its head: In the kind warmth the metal learns to glow, And pure from dross the silver runs below. S. Wesley.
Gill's Exposition of the Entire BibleFor thou shall heap coals of fire upon his head,.... Not to increase his punishment and damnation, the more aggravated by kindness shown him; but to bring him by such means to a sense of former injuries, and to shame for them, repentance of them, and love of the person injured, and carefulness for the future of doing him any further wrong; and the Lord shall reward thee: with good things, for all the good done to thine enemy, whether it has the desired effect on him or not; or whether he rewards thee or not; see Romans 12:20.
Geneva Study BibleFor thou shalt heap {p} coals of fire upon his head, and the LORD shall reward thee. (p) You will, as if by force, overcome him, in so much that his own conscience will move him to acknowledge the benefits, and his heart will be inflamed.
Wesley's Notes 25:22 For - In so doing, which words are expressed Rom 12:20, where this text is quoted. Thou shalt melt him into repentance, and love.
Matthew Henry's Concise Commentary25:19. Confidence in an unfaithful man is painful and vexatious; when we put any stress on him, he not only fails, but makes us feel for it. 20. We take a wrong course if we think to relieve those in sorrow by endeavouring to make them merry. 21,22. The precept to love even our enemies is an Old Testament commandment. Our Saviour has shown his own great example in loving us when we were enemies. 23. Slanders would not be so readily spoken, if they were not readily heard. Sin, if it receives any check, becomes cowardly. 24. It is better to be alone, than to be joined to one who is a hinderance to the comfort of life. 25. Heaven is a country afar off; how refreshing is good news from thence, in the everlasting gospel, which signifies glad tidings, and in the witness of the Spirit with our spirits that we are God's children! 26. When the righteous are led into sin, it is as hurtful as if the public fountains were poisoned. 27. We must be, through grace, dead to the pleasures of sense, and also to the praises of men. 28. The man who has no command over his anger, is easily robbed of peace. Let us give up ourselves to the Lord, and pray him to put his Spirit within us, and cause us to walk in his statutes.
Matthew Henry's Whole Bible CommentaryVerses 21-22 By this it appears that, however the scribes and Pharisees had corrupted the law, not only the commandment of loving our brethren, but even that of loving our enemies, was not only a new, but also an old commandment, an Old-Testament commandment, though our Saviour has given it to us with the new enforcement of his own great example in loving us when we were enemies. Observe, 1. How we must express our love to our enemies by the real offices of kindness, even those that are expensive to ourselves and most acceptable to them: "If they be hungry and thirsty, instead of pleasing thyself with their distress and contriving how to cut off supplies from them, relieve them, as Elisha did the Syrians that came to apprehend him," 2 King 6:22. 2. What encouragement we have to do so. (1.) It will be a likely means to win upon them, and bring them over to be reconciled to us; we shall mollify them as the refiner melts the metal in the crucible, not only by putting it over the fire, but by heaping coals of fire upon it. The way to turn an enemy into a friend is, to act towards him in a friendly manner. If it do not gain him, it will aggravate his sin and punishment, and heap the burning coals of God's wrath upon his head, as rejoicing in his calamity may be an occasion of God's turning his wrath from him, ch. 24:17. (2.) However, we shall be no losers by our self-denial: "Whether he relent towards thee or no, the Lord shall reward thee; he shall forgive thee who thus showest thyself to be of a forgiving spirit. He shall provide for thee when thou art in distress (though thou hast been evil and ungrateful), as thou dost for thy enemy; at least it shall be recompensed in the resurrection of the just, when kindnesses done to our enemies shall be remembered as well as those shown to God's friends." | 
