Treat every man not with flattery, but simply, just as you do yourself. As you appear to him outwardly, be so inwardly as well; and what you say to him and what you have on your lips must be in your heart also. For flattery and treachery are the works of pestilent people, and the devil lives in their heart teaching them flattery and treachery so as to deceive us.
Keep, then, from treating your neighbor craftily and treacherously, lest you give place to the devil in your heart, and lest he overcome you and take you captive.
Be extremely careful not to offend anyone in word or deed, for it is a grave sin. When someone is offended, God, Who loves the man, is also offended, for there can be no offending man without offending God. Whoever sins against man, also sins against God. This is a serious matter, as you can see for yourself. And when you offend your neighbor, straightway humble yourself before him and beg forgiveness of him with humility, lest you fall under God's just condemnation.
Keep from prying into other people's affairs, for such prying gives occasion for slander, judgment and other grievous sins. Why do you need to be concerned about others? Know and examine your own self.
Recall your own past sins and purge them with repentance and contrition of heart, and you will not look at what other people do. Look often into your own heart and examine that most ruinous evil hidden there, and you will have sufficient material for investigation. For we can never examine our heart without knowing precisely that every evil is contained in it.
This investigation is profitable to you, for it gives birth to humility and to fear and watching over one's own self, and to sighing and prayer to God. But examination of the sins of others is the beginning of every iniquity and it is a curiosity hateful to God and man. Then guard yourself against it.
If you see or hear someone sin, keep from slandering him and judging him. You tell someone else about him, he tells it to another, the other to the third, the third to the fourth, and so everyone will come to know it and be tempted. And they will judge the one who sinned, which is a very serious thing. And you will be the cause of all this, by publishing your brother's sin. Slanderers are like lepers that harm others by their foul odor, or like those stricken by the plague who carry their disease from place to place and destroy others. Keep yourself, then, from slandering your neighbor, lest you sin gravely and give someone else cause for sin.
Likewise keep from judging him, because he stands or falls before his Lord (cf. Rom. 14:4), and because you yourself are a sinner. A righteous man has no need to judge and condemn another, how much less should a sinner judge a sinner.
And to judge people is a matter for Christ alone. To Him judgement is given by His Heavenly Father, and He shall judge the living and the dead, before Whose judgement you yourself will stand.
Keep, then, from usurping to yourself the authority of Christ, which is a very serious thing, and from judging people like unto yourself, lest you appear at that Judgement with this most abominable sin, and lest you be rightly condemned to everlasting punishment. Turn your eyes and mind, then, on your own self and examine yourself, and reproach and accuse yourself before God for your sins, which requires the labor of repentance. Reproach and accuse yourself before God and beg mercy of Him, as the publican did, so that you may be justified by Him.
Listen to what Christ the Lord says to the condemned, "And why dost thou behold the mote that is in thy brother's eye, but considerest not the beam that is in thine own eye? Or how wilt thou say to thy brother, Let me pull out the mote out of thine eye; and, behold, a beam is in thine own eye? Thou hypocrite, first cast out the beam out of thine own eye; and shalt then thou see clearly to cast out the mote out of brother's eye" (Mt. 7:3-5).
You see that those that judge and condemn others are hypocrites or false Christians. These do not know themselves and their own sins, although outwardly they may appear as saints.
St. Tikhon of Zadonsk