What is more grievous than the sin of condemning one's neighbour?

"What is more grievous than the sin of condemning one's neighbour? What else is so hateful and alienating to God? And yet a person comes to this great evil through something seemingly unimportant - from allowing himself a small censure of his neighbour. For when this is allowed the mind begins to leave its own sins without attention and notice the sins of its neighbour. And this leads to gossip, reproaches, speaking evil and, finally, pernicious condemnation. Yet nothing angers God more, nothing despoils a person and leads so surely to perdition as fault-finding, speaking evil and condemning one's neighbour." Paragraph 34

"At times we not only condemn but bring our neighbor into contempt. For it is one thing to condemn, and another to bring into contempt. To bring into contempt means when a person not only condemns but also despises another, scorns him and turns away from him as from an abomination. This is worse than condemnation and much more pernicious." Para. 38

"Those who want to be saved pay no attention to the failings of their neighbours, but always look for their own and make progress" Para. 39

- Directions on Spiritual Training by Dorotheus of Gaza (6th century)