John Chrysostom on Self-Judgment

Let us not be overcurious about the failings of others, but take account of our own; let us reckon up the excellences of other men, while we bear in mind our faults; and thus shall we be well pleasing to God.

For he who looks at the faults of others, and at his own excellences, is injured in two ways: by the latter he is carried up to arrogance, through the former he falls into listlessness. For when he perceives that such a one has sinned, very easily will he sin himself; when he perceives that he has in anything excelled, very easily he becomes arrogant. He who consigns to oblivion his own excellences, and looks at his failings only, while he is a curious enquirier of the excellences--not the sins--of others, he is profited in many ways.

And how? When he sees that such a one has done excellently, he is raised to emulate the same; when he sees that he himself has sinned, he is rendered humble and modest. If we act thus, if we thus regulate ourselves, we shall be able to obtain the good things which are promised, through the grace and lovingkindness of our Lord Jesus Christ.-- from Homilies on Philippians