Catechism of the Catholic Church §2547 — excerpt
The Lord grieves over the rich, because they find their consolation in the abundance of goods. "Let the proud seek and love earthly kingdoms, but blessed are the poor in spirit for theirs is the Kingdom of heaven."
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: St. Augustine, De serm. Dom. in monte 1, 1, 3: PL 34, 1232