Pro 25:21 If thine enemy be hungry, give him bread to eat; and if he be thirsty, give him water to drink:
Pro 25:22 For thou shalt heap coals of fire upon his head, and the LORD shall reward thee.
These verses are referred to in Romans 12.
Rom 12:19 Dearly beloved, avenge not yourselves, but rather give place unto wrath: for it is written, Vengeance is mine; I will repay, saith the Lord.
Rom 12:20 Therefore if thine enemy hunger, feed him; if he thirst, give him drink: for in so doing thou shalt heap coals of fire on his head.
Rom 12:21 Be not overcome of evil, but overcome evil with good.
If your enemy is hungry, feed him, if thirsty, give him something to drink. This will be like heaping coals on his head. Now some say the coals are an act of giving someone a fire starter as there were no matches. That is really stretching this story. He was not given coals actual coals upon his head, but spiritual coals. It was meant as conviction of wrong doing and a possible rethinking of the relationship with the one who gave him kindness; food and drink.
If we are to bring a person who is an enemy of God to repentance and to a better disposition towards hearing our message, it is better to be kind, to show that we mean the person no harm. It is God he should fear and God that may take vengeance. If we do well we are not under condemnation. If he repents and comes to Jesus he then becomes a friend with Jesus Christ and his followers. Our loving concern is better than strife, anger and evil doing. He may still continue to hate you and your message, but that is on them, not you. We want to see them saved and escaping wrath and hell. Wrath belongs to God and so does salvation and a new life for those who trust in him and Jesus the savior from sins. May we put away hurt and vengeance and put on love and a burning desire to save the lost.