Catechism of the Catholic Church §2189 — excerpt
"Observe the sabbath day, to keep it holy" (Deut 5:12). "The seventh day is a sabbath of solemn rest, holy to the Lord" (Ex 31:15).
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.