If someone is not under obedience to you, do not rebuke him to his face for his faults. For that would imply you have authority over him, and are not just giving advice.
What is said without explicit reference to individuals is helpful to all, for each applies it to himself according to his own conscience. If you speak rightly, you should recognize that you receive the words from God. For the truth belongs not to you who speak, but to God who is energizing you.
Do not argue with people not under obedience to you when they oppose the truth; otherwise you may arouse their hatred.
If you give way when someone who is under obedience to you wrongly contradicts you, you lead him astray over the point at issue and also encourage him to repudiate his promise of obedience.
The one who with fear of God admonishes or corrects someone who has sinned, gains the virtue that is opposite to that sin. But the one who reproaches someone out of rancor and ill will becomes subject to a similar passion, according to the spiritual law.
The one who has learned the law properly fears the Lawgiver and, fearing Him, he turns away from every evil.
Based on Saint Mark the Ascetic