Roman Catechism 29.11

Chapter 29 — Part III: The Decalogue — The Sixth Commandment

Section 11. Purity Enjoined — We now come to explain the positive part of the precept. The faithful are to be taught and earnestly exhorted to cultivate continence and chastity with all care, to cleanse themselves from all defilement of the flesh and of the spirit, perfecting sanctification in the fear of God.