But the tax collector stood off at a distance and would not even raise his eyes to heaven but beat his breast and prayed, ‘O God, be merciful to me a sinner.’ (Lk 18:9-14)
https://bible.usccb.org/bible/readings/030924.cfm
The Jesus Prayer (“Lord Jesus Christ, Son of God, have mercy on me”) is an ancient prayer of Christian spirituality and comes from the parable of the Pharisee and the Tax Collector. The Desert Fathers and Mothers recommended the Jesus Prayer to their disciples and bequeathed its profound simplicity to us. The heart of all prayer is the name of Jesus. As the Catechism reminds us: The Hail Mary reaches its high point in the words “blessed is the fruit of thy womb, Jesus” (CC 435).