Catechism of the Catholic Church §2171 — excerpt
God entrusted the sabbath to Israel to keep as a sign of the irrevocable covenant. The sabbath is for the Lord, holy and set apart for the praise of God, his work of creation, and his saving actions on behalf of Israel.
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.