Chapter 26 — Part III: The Decalogue — The Third Commandment
Section 20. We sanctify the Sabbath fully and perfectly, therefore, when we offer to God works of piety and religion. This is evidently the Sabbath, which Isaias calls delightful; for festivals are, as it were, the delight of God and of pious men. And if to this religious and holy observance of the Sabbath we add works of mercy, the rewards promised us in the same chapter are numerous and most important.