Roman Catechism 19.163

Chapter 19 — Part II: The Sacraments — Penance

Section 163. Works Of Satisfaction Are Of Three Kinds — Pastors should teach that all kinds of satisfaction are reducible to three heads: prayer, fasting and almsdeeds, which correspond to three kinds of goods which we have received from God, those of the soul, those of the body and what are called external goods.