Catechism of the Catholic Church §2810 — excerpt
In the promise to Abraham and the oath that accompanied it, God commits himself but without disclosing his name. He begins to reveal it to Moses and makes it known clearly before the eyes of the whole people when he saves them from the Egyptians: "he has triumphed gloriously."
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.