Proverbs 25:22 For thou shalt heap coals of fire upon his head, and the Lord shall reward thee.
vv. 21-22 is quoted in Romans 12:20: “If your enemy is hungry, feed him; if he is thirsty, give him something to drink; for by doing so you will heap burning coals on his head.” The Holy Spirit, through Paul, says, “Do not repay evil for evil upon another flesh and blood human being, and never avenge yourselves, but leave it to the wrath of God. To the contrary, ‘if your enemy is hungry….but overcome evil with good.”
God’s command is simple: When people treat you with evil, do not repay with evil, instead overcome evil with good. Be kind to those who mistreat you. This is contrary to our natural response. For this reason He give us a twofold promise: 1) trust God to take vengeance and get justice done, and 2) believe that the Lord will reward you when you are kind to the mistreaters. That is the meaning of the “coals of fire” metaphor: be kind to all.
We don’t know what the reward will be or when it will come, but trust the promise, the Lord will reward you. Believe no act of kindness will go unnoticed or unrewarded.