Catechism of the Catholic Church §72 — excerpt
God chose Abraham and made a covenant with him and his descendants. By the covenant God formed his people and revealed his law to them through Moses.
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.