Catechism of the Catholic Church §2573 — excerpt
God renews his promise to Jacob, the ancestor of the twelve tribes of Israel. Before confronting his elder brother Esau, Jacob wrestles all night with a mysterious figure who refuses to reveal his name, but he blesses him before leaving him at dawn.
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.