15 What allowance then can be made for us, if even when we might receive so great a reward we still do not obey the Lawgiver, but persist in our contempt; for that this is a contempt is plain from hence. If the Emperor had laid down a law, that all those who were enemies should be reconciled to one another, or have their heads cut off, should we not every one make haste to a reconciliation with his neighbour? Yes! truly, I think so! What excuse then have we, in not ascribing the same honour to the Lord, that we should do to those who are our fellow-servants?
For this reason we are commanded to say, “Forgive us our debts, as we forgive our debtors.” What can be more mild, what more merciful, than this precept! He has made you a judge of the pardon of your own offenses! If you forgive few things, He forgives you few! If you forgive many things, He forgives you many! If you pardon from the heart, and sincerely, God in like manner also pardons you! If besides pardoning him you account him a friend, God will also thus deal with you; so that the more he has sinned, so much the more is it necessary that we should hasten to a reconciliation; since it becomes a cause of greater offenses being forgiven us. Are you willing to learn that there is no pardon for us, if we are mindful of injuries, and that there is no one who can deliver us?
I will make what I assert plain by an example. Suppose that a neighbour has done you a certain injury, that he has seized your goods; has confiscated or embezzled them; and not to confine myself to such a case, let me add to it more things and worse beside, and whatever you will; he has longed to destroy you; he has exposed you to a thousand perils; he has manifested every sort of malice towards you; and left nothing undone that human wickedness can do? For not to go over every thing separately, suppose that he has injured you to such an extent as no one ever injured any before—why, even in this case, if you are resentful, you will not be worthy of pardon. And I will explain how it is so.
Source: Homilies on the Statues (New Advent)