Tolstoy wrote about an honest and hardworking Russian peasant who stayed in a local inn. A man was killed that night and the murderer placed the weapon in the bag of the sleeping peasant. The police discovered it and put the hapless peasant in jail. For twenty-six years the peasant survived the harsh conditions of prison on the bitter hope that someday he would obtain revenge.
After twenty-six years the real murderer was placed in prison and then caught attempting to escape. One prisoner saw everything: the peasant. At long last the opportunity dreamed about since that villainous night twenty-six years ago presented itself, for on the peasant’s word the murderer would be put to death. Here was his big chance. If it were you; what would you do?
“Don’t get mad, get even!” is our chanted mantra. Maybe an employer treated you unfairly or a coworker climbed to the top over your back. A spouse abandoned you. Your parents failed you. You were “done wrong” as they say and now you are waiting for a chance to retaliate. “Don’t get mad, get even” is a reasonable response in the face of gross unfairness, isn’t it? No, it is not!
God calls it vengeance and has a lot to say about it. “Dear friends, never avenge yourselves. Leave that to God. For it is written, “I will take vengeance;” (Romans ) I don’t like God’s emphasis on “never avenge.” I would want to say, usually. I would seek exceptions for extreme examples like our Russian peasant, but not God. A good Biblical example would be David. 
King Saul was insanely jealous of David’s increasing popularity and eventually stripped him of his job, his wife, his best friend and his self-respect, finally forcing him to flee for safety. For years not days, Saul pursued David looking to exterminate him. But then:Saul went into a cave to relieve himself. But as it happened, David and his men were hiding in that very cave!” (1 Samuel 24:3)
Again, if it were you — what would you do? “’Now’s your opportunity!’ David’s men whispered to him. Then David crept forward and cut off a piece of Saul’s robe.” (4-5) Why did David do that? Saul was trying to kill him. Why didn’t David get even? Instead, he crept close to Saul and performed the equivalent of a teenage prank or practical joke. Even that small act of defiance made David feel guilty. “The LORD knows I shouldn’t have done it,” he said to his men.” (6)
In the military, it is drilled into you: ‘salute the rank, not the person.’ Saul was anointed by God to be King. David was duty bound to treat the King with respect and honor. David wisely chose mercy and to confront Saul with truth. As he left the cave, David appeared and held up a piece of his robe. “This proves that I am not trying to harm you and that I have not sinned against you, even though you have been hunting for me to kill me. The LORD will decide between us. Perhaps the LORD will punish you for what you are trying to do to me, but I will never harm you.” (11-12)
David’s refusal to succumb to the temptation of “getting even” was a turning point because he chose to do what was right by repaying evil with good. “If your enemies are hungry, feed them. If they are thirsty, give them something to drink., Don’t let evil get the best of you, but conquer evil by doing good.” (Romans 12:20-21) David ultimately chose to place his faith in God not revenge.
Speaking of turning points; the Russian peasant had his own opportunity to “get even” with the man who ruined his life. But instead of jumping at the chance, the story describes the peasant as experiencing the overpowering grace and love of God. The darkness that was within him was suddenly filled with light and the peasant found himself saying to the officers: “I saw nothing.”
That night the murderer approached the peasant and on his knees begged for forgiveness. Again, the light of Christ flooded the peasant’s heart: “God will forgive you. Maybe I am a hundred times worse.” And at those words the peasant’s heavy heart grew light as he received God’s comfort.
I don’t know of any better witness to your faith in God than a willingness to forgive someone who has grievously harmed you.

Is it easy? Never! Is it necessary and worthwhile? Absolutely! Your willingness to forgive could be the principal turning point in your life, your health and your faith.