In Mark 11:25, Jesus says, “Whenever you stand praying, forgive, if you have anything against anyone, so that your Father who is in heaven will also forgive you your transgressions.
Not only are we commanded by Jesus Himself to forgive others, it is to our benefit to do so. The opposite is un-forgiveness which is at the root of all bitterness. Harboring bitterness is detrimental to not only our souls but our health as well.
Besides, we would do good to always remember how great a debt we owed a holy God because of our sinfulness and how He in His grace and mercy forgave us of all our sins, past, present and future. How then can we hold anything against anyone?
Here is a secular infographic that looks at the power of forgiveness. If forgiving is good medicine for those without faith in Christ, how much more is is good medicine for us?
[Click image for full size version]