Catechism of the Catholic Church §2742 — excerpt
"Pray constantly . . always and for everything giving thanks in the name of our Lord Jesus Christ to God the Father." St. Paul adds, "Pray at all times in the Spirit, with all prayer and supplication.
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.
Also cites: Evagrius Ponticus, Pract. 49: PG 40, 1245C