"The heedless person forgets to put an end to a quarrel; the stubborn one is loath to grant pardon when asked; the person who is proudly ashamed disdains to beg pardon. Animosities live on in these three vices, but they kill the soul in which they don't die. Let a spirit of recollection keep watch against heedlessness, of compassion against vindictive stubbornness, of gentle good sense against proud shame. If you recall that you have neglected to make it up with someone, then wake up and shake off your torpor. If you are so keen to exact payment from your debtor, just think for a moment that you are God's debtor. If you are ashamed to ask your brother or sister to forgive you, overcome this bad sort of shame with a good sort of fear, so that with destructive animosities terminated, with them finally dead, you yourselves may live.
"All this is the work of charity, which does not act crookedly. So let charity, my brothers and sisters, insofar as it is present among you, be exercised by your living good lives; while insofar as there is little of it there, let it be obtained by your praying for it."
Augustine of Hippo (AD 354-430), Sermon 209, 1