St. John Cassian: Nothing is to be preferred to love

 Just as nothing is to be preferred to love, then, so also, on the other hand, nothing is to be less esteemed than rage and wrath. For everything, however beneficial and necessary it may appear, should nonetheless be put aside in order to avoid the disturbance of anger, and everything that may seem inimical should be put up with and tolerated in order to maintain unharmed the tranquility of love and peace, for it must be believed that nothing is more destructive than anger and annoyance and nothing more beneficial than love.

+St. John Cassian, from The Conferences, Conference 16; On Friendship #7

St. Seraphim of Sarov: On Spiritual Peace

 We can see how to defeat anger in the life of St. Paisius the Great. He asked the Lord Jesus Christ, Who appeared to him, to release him from anger. But Christ answered him, "If you want to defeat anger and wrath together, desire nothing, hate no one, humiliate no one."¹To preserve peace of soul you must keep despair at bay and try to preserve a joyful disposition, not a sorrowful one. As the wise Sirach said, "For sorrow has destroyed many, and there is no profit in it" (Sirach 30:23). To preserve peace of soul, you must in every way avoid condemnation of others. By you lack of judgment and your silence, you will preserve spiritual peace. When a man is in such a state, he receives divine revelations.

+St. Seraphim of Sarov, from Spiritual Instructions, #3-4 On the Peace of the Soul and Preserving It.

¹ from the Life of St. Paisius the Great in The Great Synaxaristes, June 19

St. Macarius the Great: Three anecdotes from his life

 One day someone asked [St. Macarius] how to make progress on the path to salvation. The saint sent him to the cemetery, first to insult the dead then to praise them, and when he came back, he said: "Look, the corpses said not a word to you in reply. Similarly, if you want to be saved you too must become like a dead man, making as little of the contempt of men as of their praises."

...

He acquired expert knowledge of the different kinds of demon. He said that they can be divided into two main categories: one consisting of the spirits which arouse passions such as anger and covetousness; and the other, more dreadful, of the spirits which mislead men by spiritual illusion, blasphemy and heresies.

...

His exceeding charity led him to pray with tears even for the damned. One day as he was walking in the desert, he came upon the skull of a pagan priest, which addressed him, saying: "Each time that you have pity on those who are in torments - on us who are plunged into the fire with our faces pressed against the backs of the one's in front - we receive a measure of comfort in being able for a while to see the faces of our fellow sufferers."

+St. Macarius the Great of Egypt, from his life in The Synaxarion Volume 3, entry for January 19.

St. Seraphim of Sarov: Acquire the spirit of peacde

 My joy, acquire the spirit of peace and then the souls of thousands around you will be saved.

+St. Seraphim of Sarov, from The Synaxarion, Volume 3, in his entry for January 2nd.

Abbess Thaisia: When we are treated unkindly

 You write: "I notice that some of the sisters treat me unkindly, and at this I become disturbed."  Many "unskilled" souls, those not "made perfect in the love of Christ" (cf 1 John 4:18) suffer from this infirmity.... As fire sometimes kindles into a mighty blaze from a little spark which was not extinguished in time, so also from a small spark of distrust and unkindness a whole flame of enmity breaks out, devouring many years of labor in virtue. If in fact a sister, through her weakness, shows you negligible kindness, then before blaming her for this look in your own heart, examine your own attitude toward her. Perhaps an attentive and impartial self-examination will prove to you that you yourself gave cause for this, and therefore are guilty in all. Strive to preserve in your heart absolute peace towards everyone, according to the word of the Apostle: "If it be possible, as much as lies in you, live peaceably with all men" (Rom 12:18). This inner peace of your own soul serves as the best pledge or security that others will have peace and love towards you; and there is nothing higher or more honorable than love, as also the Apostle affirms, calling love "the fulfillment of (all) law" (Rom 13:8) and "the bond of perfectness" (Col 3:14), in the presence of which "the peace of God settles in our hearts" (cf. Philip 4:7).

+Abbess Thaisia, from Letters to a Beginner On Giving One's Life to God, Letter #5 On Mutual Love.

St. Seraphim of Sarov: On Preserving Spiritual Peace

It is necessary to strive to preserve one's spiritual peace by any means possible. Do not be upset by the insults of others. Strive in every possible way to restrain yourself from anger and to guard attentively both your heart and mind against unbefitting emotions.
Therefore tolerate the insults of others with equanimity and try to preserve your disposition as if these were not directed at you. Such and exercise will bring peace to your heart and prepare it as an abode for God Himself.
We see an example of such forbearance in the life of St. Gregory the Wonderworker, when a certain prostitute publicly demanded that he compensate her for an alleged sinful encounter with her. He, not becoming in the least angry, meekly told his friend to give her the money she was demanding. The woman had no sooner taken the money than she fell subject to an attack of a demon. Then the holy one prayed and drove the demon from her.
If on the other hand, you find it impossible not to become offended, then at least you should try to hold your tongue, for as the Psalmist said, "I was troubled and did not speak."(Psalms 77:4)
+St. Seraphim of Sarov, from Spiritual Instructions, On Preserving Spiritual Peace, in The Joy of the Holy.