Catechism of the Catholic Church §174 — excerpt
"For though languages differ throughout the world, the content of the Tradition is one and the same. the Churches established in Germany have no other faith or Tradition, nor do those of the Iberians, nor those of the Celts, nor those of the East, of…
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.
Also cites: St. Irenaeus, Adv. haeres. I, 10, 1-2: PG 7/1, 552-553 · St. Irenaeus, Adv. haeres. 5, 20, I: PG 7/2, 1177