Council of Trent: Session XIV, On The Most Holy Sacrament Of Penance, Canon XIII

ON THE MOST HOLY SACRAMENT OF PENANCE

CANON XIII.--If any one saith, that satisfaction for sins, as to their temporal punishment, is nowise made to God, through the merits of Jesus Christ, by the punishments inflicted by Him, and patiently borne, or by those enjoined by the priest, nor even by those voluntarily undertaken, as by fastings, prayers, almsdeeds, or by other works also of piety; and that, therefore, the best penance is merely a new life; let him be anathema.

Translation: J. Waterworth, The Canons and Decrees of the Council of Trent (1848), Hanover Historical Texts Project transcription (1995).