Catechism of the Catholic Church §2862 — excerpt
The fifth petition begs God's mercy for our offences, mercy which can penetrate our hearts only if we have learned to forgive our enemies, with the example and help of Christ.
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.