Vengeance is The Lord's

Romans 12:19-21

Dearly beloved, avenge not yourselves, but rather give place unto wrath: for it is written, Vengeance is mine; I will repay, saith the Lord.
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. Be not overcome of evil, but overcome evil with good.

Proverbs 24:29
Say not, I will do so to him as he hath done to me: I will render to the man according to his work.