Catechism of the Catholic Church §256 — excerpt
St. Gregory of Nazianzus, also called "the Theologian", entrusts this summary of Trinitarian faith to the catechumens of Constantinople: Above all guard for me this great deposit of faith for which I live and fight, which I want to take with me as a companion,…
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. Gregory of Nazianzus, Oratio 40, 41: PG 36,417