Roman Catechism 19.93

Chapter 19 — Part II: The Sacraments — Penance

Section 93. After His Resurrection He breathed on the Apostles, assembled together, saying: Receive ye the Holy Ghost, whose sins you shall forgive, they are forgiven; and whose sins you shall retain, they are retained. Now in giving to priests the power to retain and forgive sins, it is evident that our Lord made them also judges in this matter.