Vengeance is a weakness in man's soul. As a higher life form we should be able to slough off the chains of petty paybacks. However, many times we cannot. We are merely human and we can't be perfect right? Right. That is why God has instructed us to forgive and give everything up to Him so that He can do the appropriate paybacks as necessary. Just give it all up to God. It will keep you out of trouble.