Saint Maximos the Confessor. "Four Hundred Texts on Love". From Philokalia, Vol. 2.
73. He who speaks dispassionately of his brother’s sins does so either to correct him or to benefit another. If he speaks for any other reason, either to the brother himself or to another person, he speaks to abuse him or ridicule him. In this case he will not escape being abandoned by God. On the contrary, he will fall into the same sin or other sins and, censured and reproached by other men, will be put to shame.
42. If you have no thought of any shameful word or action in your mind, harbor no rancor against someone who has injured or slandered you, and, while praying, always keep your intellect free from matter and form, you may be sure that you have attained the full measure of dispassion and perfect love.
53. A man can enjoy partial dispassion and not be disturbed by passions when the objects which rouse them are absent. But once those objects are present, the passions quickly distract his intellect.
54. Do not imagine that you enjoy perfect dispassion when the object arousing your passion is not present. If when it is present you remain unmoved by both the object and the subsequent thought of it, you may be sure that you have entered the realm of dispassion. But even so do not be over-confident; for virtue when habitual kills the passions, but when it is neglected they come to life again.
92. If when some trial occurs you cannot overlook a friend’s fault, whether real or apparent, you have not yet attained dispassion. For when the passions which lie deep in the soul are disturbed, they blind the mind, preventing it from perceiving the light of truth and from discriminating between good and evil. If you are in such a state you have likewise not yet attained perfect love, the love which expels the fear of judgment (cf. 1 John 4:18).