Abba Isaiah of Scetis: Faith in Temptations

 A person who doubts whether God will help him during temptations does not believe in God and is not worthy to be called Christian. A truly believing and pious person, even if he finds himself in the very jaws of the serpent, still believes, even then, that God can rescue him. Thus did the martyrs believe and they fearlessly entered the flaming furnace, and God delivered them because of their unwavering faith. In this way He delivered the Three Youths from the Babylonian furnace, and St. Thekla from the fire and the cruel beasts - all, without a doubt, because of their pure faith.

+Abba Isaiah of Scetis, from Matericon Instructions of Abba Isaiah to the honorable nun Theodora, #52

Abba Isaiah of Scetis: On Slander and humility

 If a brother harms you and someone else slander him in front of you, guard your heart so that evil is not revived so that evil is not revived within you. Instead, remember your own sins before God and that you want Him to forgive you these, and "do not return evil" (Rom 12:17)  against your neighbor.

If you are out with brothers who are unknown to you and there happen to be younger than you, give them the honor of priority. If you visit the house of a friend, allow the other precedence over you in everything, whether at the washing basin or at the dinner table. And do not give yourself priority because you are supposedly their guest, but allow them the honor, saying, "God has been merciful to me on account of you".

+Abba Isaiah of Scetis, from Ascetic Discourses, discourse 4.

Abba Isaiah of Scetis: Not judging one's neighbor

Not judging one's neighbor is a protection for those who struggle in knowledge, but blaming one's neighbor destroys this protection in ignorance. Taking care of one's tongue¹ is the sign a person who practices the virtues. Not controlling one's tongue shows that a person has no inner virtue. Goodness gives rise to purity. Distraction give rise to passions, and hardheartedness gives rise to anger. Discipline of the soul is hatred of distraction, and disciple of the body is poverty. The fall of the soul is loving distraction, and its rise is silence in knowledge. Excessive sleep disturbs the passions within the body, and vigil in measure is the heart's salvation. Too much sleep thickens the heart, but vigil in measure refines it. It is better to sleep in silence and knowledge, than to keep vigil with idle talk. Compunction calmly expels all evil. Not offending your neighbor's conscience gives rise to humility. Human glory very gradually gives rise to pride. Loving to boast expels knowledge.
+Abba Isaiah of Scetis, from Ascetic Discourses, Discourse 16 On the Joy that Comes to the Soul that Desires to Serve God.

¹ St. John Climacus, from The Ladder, Step 22