The Jesus Prayer, also called the Prayer of the Heart, the Prayer of a Single Thought, or simply The Prayer, is a short, simple prayer that has been widely used, taught and discussed throughout the history of Eastern Christianity. The exact words of the prayer have varied, from a simple form such as "Lord, have mercy" to an extended form: "Lord Jesus Christ, Son of God, have mercy on me, the sinner." or "Lord Jesus Christ, Son of God, have mercy on me, a sinner."