Matteo 6:14-15

A necessary warning: For if ye forgive men their trespasses, your heavenly Father will also forgive you. But if ye forgive not men their trespasses, neither will your Father forgive your trespasses.

The hearing of our prayer, the granting of the benefits asked for, hinges upon our being in the right relation toward God, which is brought about by the assurance and the certainty of the forgiveness of sins. And this, in turn, depends upon the manner in which we show proofs of the right condition of our hearts toward the neighbor. Our sins toward God were called debts, and these are piled up with horrible swiftness.

Our neighbor's sins toward us are described as mere stumblings or faults in performing his duty. To be vindictive under such circumstances is folly in itself, and argues that the mercy of God is not appreciated. If we really desire the forgiveness of God, we must first show that we realize our own sinfulness and its damnableness by forgiving our neighbor his faults.