Catechism of the Catholic Church §146 — excerpt
Abraham thus fulfils the definition of faith in Hebrews 11:1: "Faith is the assurance of things hoped for, the conviction of things not seen": "Abraham believed God, and it was reckoned to him as righteousness."
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.