The Jesus Prayer

Lord Jesus Christ, Son of God,have mercy on me, a sinner.
This prayer joins the cry of the blind man at Jericho (Luke 18:38) with the prayer of the publican in the Temple (Luke 18:13). It is prayed slowly, often in time with the breath, so that, as the Catechism says, the invocation of the holy name of Jesus becomes the simplest way of praying always.
In Latin
Iesu, Christe, Fili Dei, Domine,miserere nobis, peccatoribus!
The Catechism gives the prayer in this form, “have mercy on us sinners”.
Latin text: Catechismus Catholicae Ecclesiae, 2667.