1) Elder Arsenia Papacioc of Romania
To the devil, we don’t need to give explanations … If you want to drive him away, say: “Lord Jesus Christ have mercy on me”, and speak to God. The power of His Name will rid him. It suits the devil to enter into a dialogue for it means that you acknowledge him. Thus through prayer, we ignore him.
2) St Barsanuphius of Optina
The prayer of Jesus is of tremendous importance in the life of a Christian. This is the shortest path to reaching the Kingdom of Heaven, although this path is not easy, and, having entered upon it, we must be ready for sorrow. True, other prayers are also of considerable importance, and a person who is praying the Jesus prayer, hears prayers and hymns in the church, makes the necessary cell rules. And yet, it is the Jesus prayer that most quickly leads a person to a penitential mood and shows him his infirmity, therefore, bringing him closer to God. Man begins to feel that he is the greatest sinner, and this is all God needs.
3) St Paisios of Mt Athos
We should always say the Jesus prayer wherever we are; not just in the morning or at night. When we walk, we should not waste our free time, but instead take advantage of it and repeat the prayer. When we are working in a busy place and it is difficult for us to concentrate on praying, we can quietly chant without disturbing others.”Lord Jesus Christ, Son of God, have mercy on me a sinner.”
4) Elder Ephraim of Arizona
The Holy Fathers were illumined and left us these little prayers. A few words: “Lord Jesus Christ, have mercy on us” and “Most Holy Theotokos, save us”. We don’t need to read encyclopedias, nor many books. With these two little prayers, all Christians are saved.
5) Random
“And what is more valuable, the Jesus prayer or the Gospel?” Asked the captain. “They are equal in importance,” I answered, “because the holy name of Jesus Christ contains within itself all the truths of the Gospel. The holy Fathers say that the prayer is the abbreviated form of the Gospel.””Lord Jesus Christ, Son of God, have Mercy on me a sinner.”
6) St Ignatius Brianchanninov
To say the Jesus Prayer a hundred times attentively and without haste about half an hour is needed, but some ascetics require even longer. Do not say the prayers hurriedly, one immediately after another. Make a short pause after each prayer, and so help the mind to concentrate. Saying the prayer without pauses distracts the mind. Breathe with care, gently and slowly.
7) St Seraphim of Sarov
‘Lord Jesus Christ, Son of God, have mercy on me a sinner’: let all thine attention and training be in this. Walking, sitting, doing, and standing in church before the divine service, coming in and going out, keep this unceasingly on thy lips and in thy heart.
8) Elder Joseph the Hesychast
Keep saying the prayer! Lord Jesus Christ, have mercy on me! Lord Jesus Christ, have mercy on me! This is what will save you. The name of Christ will illumine your mind (nous); it will strengthen your soul; it will help you in the war against the demons; it will cultivate the virtues; and it will become everything for you.
9) St Ignatius Brianchaninov (2)
The name of our Lord Jesus Christ is a divine name. The power and effect of that name are divine, omnipotent and salvific, and transcend our ability to comprehend it. With faith therefore, with confidence and sincerity, and with great piety and fear ought we to proceed to the doing of the great work which God has entrusted to us: to train ourselves in prayer by using the name of our Lord Jesus Christ. “The incessant invocation of God’s name,” says Barsanuphius the Great, “is a medicine which mortifies not just the passions, but even their influence. Just as the physician puts medications or dressings on a wound that it might be healed, without the patient even knowing the manner of their operation, so also the name of God, when we invoke it, moritifes all passions, though we do not know how that happens”
10) Metropolitan Anthony Bloom
More than any other prayer, the Jesus Prayer aims at bringing us to stand in God’s presence with no other thought but the miracle of our standing there and God with us, because in the use of the Jesus Prayer there is nothing and no one except God and us.
The Art of Orthodoxy 