2. So the fathers of the fourth Council of Constantinople, following the footsteps of their predecessors, published this solemn profession of faith: The first condition of salvation is to maintain the rule of the true faith. And since that saying of our lord Jesus Christ, You are Peter, and upon this rock I will build my Church [55], cannot fail of its effect, the words spoken are confirmed by their consequences. For in the Apostolic See the Catholic religion has always been preserved unblemished, and sacred doctrine been held in honor. Since it is our earnest desire to be in no way separated from this faith and doctrine, we hope that we may deserve to remain in that one communion which the Apostolic See preaches, for in it is the whole and true strength of the Christian religion [56].
"Si quis dixerit, receptos et approbatos ecclesiae catholicae ritus in solemni sacramentorum administratione adhiberi consuetos aut contemni, aut sine peccato a ministris pro libito omitti, aut in novus alio per quemcumque ecclesiarum pastorem mutari posse: anathema sit." - -Session VII, Canon 13
"If anyone says that the received and approved rites of the Catholic Church, accustomed to be used in the administration of the Sacraments, may be despised or omitted by the ministers without sin and at their pleasure, or may be changed by any pastor (a term that includes the Supreme Pastor, the Pope] of the churches to other new ones, let him be anathema."