Catechism of the Catholic Church §2761 — excerpt
The Lord's Prayer "is truly the summary of the whole gospel." "Since the Lord . . after handing over the practice of prayer, said elsewhere, 'Ask and you will receive,' and since everyone has petitions which are peculiar to his circumstances, the regular and appropriate…
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: Tertullian, De orat. 1: PL 1, 1155 · Tertullian, De orat. 10: PL 1, 1165