Catechism of the Catholic Church §2608 — excerpt
From the Sermon on the Mount onwards, Jesus insists on conversion of heart: reconciliation with one's brother before presenting an offering on the altar, love of enemies, and prayer for persecutors, prayer to the Father in secret, not heaping up empty phrases, prayerful forgiveness from…
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.