4 And so let us be ready to forgive all the trespasses which are committed against us, if we desire to be forgiven. For if we consider our sins, and reckon up what we do in deed, what by the eye, what by the ear, what by thought, what by numberless movements; I know not whether we so much as sleep without a talent. And therefore do we daily beg, daily knock at the ears of God by prayer, daily prostrate ourselves and say, “Forgive us our debts, as we forgive our debtors.” What debts of yours? All, or a certain part? You will answer, All. So then do you with your debtor. This then is the rule you lay down, this the condition you speak of; this the covenant and agreement you mention when you pray, saying, “Forgive us, as we forgive our debtors.”
Source: Sermons on Selected Lessons of the New Testament (New Advent)