The Jesus Prayer, also known as The Prayer, is a short formulaic prayer, esteemed and advocated especially in Eastern Christianity:
"Lord Jesus Christ, Son of God, have mercy on me, a sinner."
It is often repeated continually as a part of personal ascetic practice, its use being an integral part of the eremitic tradition of prayer known as hesychasm. The prayer is particularly esteemed by the spiritual fathers of this tradition (see Philokalia) as a method of cleaning and opening up the mind and after this the heart (kardia), brought about first by the Prayer of the Mind, or more precisely the Noetic Prayer (Νοερά Προσευχή), and after this the Prayer of the Heart (Καρδιακή Προσευχή). The Prayer of the Heart is considered to be the Unceasing Prayer that the Apostle Paul advocates in the New Testament. Theophan the Recluse regarded the Jesus Prayer stronger than all other prayers by virtue of the power of the Holy Name of Jesus.
Though identified more closely with Eastern Christianity, the prayer is found in Western Christianity in the Catechism of the Catholic Church. It also is used in conjunction with the recent innovation of Anglican prayer beads. The prayer has been widely taught and discussed throughout the history of the Eastern Catholic Church and Eastern Orthodox Church. The ancient and original form did not include the words "a sinner", which were added later.
The Eastern Orthodox theology of the Jesus Prayer as enunciated in the 14th century by Gregory Palamas was generally rejected by Latin Church theologians until the 20th century. Pope John Paul II called Gregory Palamas a saint, a great writer, and an authority on theology. He also spoke with appreciation of hesychasm as "that deep union of grace which Eastern theology likes to describe with the particularly powerful term "theosis", 'divinization, and likened the meditative quality of the Jesus Prayer to that of the Catholic Rosary.
The prayer's origin is the Egyptian desert, which was settled by the monastic Desert Fathers and Desert Mothers in the 5th century.