The “Jesus Prayer” or the “Prayer of the Heart” is one of the most beloved prayers next to the Lord’s Prayer, but not many Protestant have heard about it.
The context of the prayer can be found in Luke 18:9-14, where two men are praying. The Pharisee says, “God, I thank you that I am not like other people: thieves, rogues, adulterers, or even like this tax collector. I fast twice a week; I give a tenth of all my income” (Luke 18:10-12, NRSV).
The publican, or tax collector, instead prayed, “God, be merciful to me, a sinner!” (Luke 18:13, NRSV). And Jesus points to this man and his prayer as the one accepted by God.
As early as the second century, the Desert Fathers and Mothers took the essence of this prayer and came up with the Jesus Prayer. There are different variations of it: the shortest: “Lord Jesus Christ, have mercy on me;” and the longest: “Lord Jesus Christ, Son of the Living God, have mercy on me, a sinner.”
By calling to mind this prayer throughout the day, the ancients put into practice the idea expressed in 1 Thess. 5:16 to “pray without ceasing.”