first forgive all those who have offended you,
Only then will your prayer rise up
into the presence of God.
If you do not forgive,
it will simply remain on the earth.
When you pray, be mindful
that you are in the presence of God,
offering a priestly sacrifice.
Would it not be a shameful thing
to offer a sacrifice that was blemished?
So, as you pray to be forgiven,
first forgive those who have offended you.
Bring them to mind and pardon them,
and then you yourself will also know
(Aphrahat the Persian – d. 345AD, The Book of Mystical Chapters, pp 19-20)