St. Paul ... says, ... 'By judging another you condemn yourself' (Rom. 2:1). But men have given up weeping for their own sins and have taken judgment away from the Son. They themselves judge and condemn one another as if they were sinless.
After a man has decided to abandon his wrong ways and actually does abandon them, the first task of the enemy is to clear a space for an unhampered field of action against him. He succeeds in this by suggesting to a man, who has entered the right path, that he should act on his own, and not go for advice and guidance to the teachers of righteous life, who are always attached to the Church. A man who follows their guidance and verifies all his actions, both inner and outer, by the good judgement of his teachers - priests in their parishes in the case of laymen, experienced startzi in monasteries - cannot be approached by the enemy. Whatever he may suggest, the experienced eye will at once see where he is driving and will warn his pupil. In this way all his wiles are defeated. But if a man turns away from his teachers, the enemy will at once confuse him and lead him astray ... There are many possibilities, which do not look evil; and those he suggests... the novice, who, feeling thus free and unhampered, begins to imagine that this good state is the fruit of his own efforts, and so rests in them.
Even if a person’s sin is not only obvious, but very grievous and comes from a hardened and unrepentant heart, do not condemn him, but raise your eyes to the wondrous and incomprehensible judgments of God; then you will see that many people, formerly full of iniquity, later repented and reached a high degree of sanctity, and that, on the other hand, others, who were on a high level of perfection, fell into a deep abyss. Take care, lest you also suffer this calamity through judging others.
Never allow yourself boldly to judge your neighbor; judge and condemn no one, ... rather have compassion and pity for him, but let his example be a lesson in humility to you; realizing that you too are extremely weak and as easily moved to sin as dust on the road, say to yourself: 'He fell today, but tomorrow I shall fall.'
The Lord’s most important commandments are 'Judge not, and ye shall not be judged; condemn not, and ye shall not be condemned; forgive, and ye shall be forgiven.' Moreover, those desirous of salvation should always keep in mind the words of St. Peter Damascene, that creation takes place between fear and hope.
Be attentive, my child, that you not judge any soul. For God steps aside from the one who judges his neighbor, and he falls, in order to learn to have sympathy for his sick brother.
Keep from prying into other people's affairs, for such prying gives occasion for slander, judgement and other grievous sins. Why do you need to be concerned about others? Know and examine your own self.Recall your past sins and purge them with repentance and contrition of heart, and you will not look at what other people do.
Do not be surprised that when you draw near to virtue, grievous and intense tribulations come to you on all sides: for virtue is not considered virtue, if it does not involve hard work.
Do not rail against anyone, but rather say ‘God knows each one.’ Do not agree with him who slanders, do not rejoice at his slander and do not hate him who slanders his neighbor. This is what it means not to judge.
When you go to your spiritual father for confession, do not bring yourself as an accuser of other people, saying, 'he said this,' and 'so-and-so said that'. . . but speak about your own doings, so that you may obtain forgiveness.
Abba Or used to say this, 'Do not speak in your heart against your brother like this: 'I am a man of more sober and austere life than he is,' but put yourself in subjection to the grace of Christ, in the spirit of poverty and genuine charity, or you will be overcome by the spirit of vainglory and lose all you have gained. For it is written in the Scriptures: 'Let him who stands take heed lest he fall.' (I Corinthians 10:12) Let your salvation be founded in the Lord.'