Proverbs 25:21
20 Like one who takes off a garment on a cold day or like vinegar poured on soda, so is one who sings songs to a heavy heart. 21 If your enemy is hungry, give him food to eat, and if he is thirsty, give him water to drink, 22 for you will heap coals of fire on his head, and the Lord will reward you. 23 The north wind brings forth rain,and a gossiping tongue brings forth an angry look. 24 It is better to live on a corner of the housetop than in a house in company with a quarrelsome wife. 25 Like cold water to a weary person, so is good news from a distant land.
Matthew 5:44
43 “You have heard that it was said, ‘Love your neighbor’ and ‘hate your enemy.’ 44 But I say to you, love your enemy and pray for those who persecute you, 45 so that you may be like your Father in heaven, since he causes the sun to rise on the evil and the good, and sends rain on the righteous and the unrighteous. 46 For if you love those who love you, what reward do you have? Even the tax collectors do the same, don’t they? 47 And if you only greet your brothers, what more do you do? Even the Gentiles do the same, don’t they? 48 So then, be perfect, as your heavenly Father is perfect.
Notes and References
"... In a temple setting, the petitioner relinquishes to God the task of judging one’s enemies. The Psalms often supplicate the Lord to deal with enemies of righteousness. Almost half of the Psalms mention enemies, making them a very common issue addressed in the Temple. The Lord smites them, turns them back, and cuts them off; vengeance is the Lord’s, as the Psalms frequently say (Psalms 58:10; 94:1; 99:8; 149:7)—a sentiment reflected by Paul: “Repay no one evil for evil, but take thought for what is noble in the sight of all ... Never avenge yourselves, but leave it to the wrath of God” (Romans 12:17, 19). Some texts rather grimly encouraged people to be nice to their enemies in order to heap coals of God’s wrath upon their heads (Proverbs 25:21–2), but there is no reason to believe that any such maliciously motivated kindness would influence how God might choose to impose his judgment. Rather, the only purpose of praying for one’s enemies would be to show love, hoping that they will repent or be spared long enough in order to repent. The antithetical actions of taking vengeance and bearing a grudge are the opposite of love, and thus the full verse in Leviticus 19, upon which this entire section of the Sermon on the Mount is based ..."
Welch, John W. The Sermon on the Mount in the Light of the Temple (p. 110) Ashgate, 2009