If you love Christ you must keep the passion of rancour far from your soul. You should on no account yield to feelings of hostility: rancour lurking in the heart is like fire hidden in stalks of dry flax. Rather you should pray fervently for anyone who has grieved you, and you should help them if you have the means. By this action your soul will be delivered from death (Tobit 4:10) and nothing will hinder your communication with God when you pray.
The Lord dwells in the souls of the humble; but shameful passions fill the hearts of the proud. Nothing so strengthens these passions against us as arrogant thoughts, and nothing uproots the evil herbs of the soul so effectively as blessed humility. Hence humility is rightly called the executioner of passions.
-St Theodoros the Great Ascetic