Romans 12:17-21  NAS          

Never pay back evil for evil to anyone.  Respect what is right in the sight of all men.  If possible, so far as it depends on you, be at peace with all men.  Never take your own revenge, beloved, but leave room for the wrath of God, for it is written, "VENGEANCE IS MINE, I WILL REPAY," says the Lord.  "BUT IF YOUR ENEMY IS HUNGRY, FEED HIM, AND IF HE IS THIRSTY, GIVE HIM A DRINK; FOR IN SO DOING YOU WILL HEAP BURNING COALS ON HIS HEAD."  Do not be overcome by evil, but overcome evil with good.