Catechism of the Catholic Church §215 — excerpt
"The sum of your word is truth; and every one of your righteous ordinances endures forever." "and now, O LORD God, you are God, and your words are true"; this is why God's promises always come true.
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.