Catechism of the Catholic Church §1128 — excerpt
, by virtue of the saving work of Christ, accomplished once for all. It follows that "the sacrament is not wrought by the righteousness of either the celebrant or the recipient, but by the power of God."
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: Council of Trent (1547): DS 1608 · St. Thomas Aquinas, STh III, 68, 8