Catechism of the Catholic Church §1014 — excerpt
The Church encourages us to prepare ourselves for the hour of our death. In the litany of the saints, for instance, she has us pray: "From a sudden and unforeseen death, deliver us, O Lord"; to ask the Mother of God to intercede for us…
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: Roman Missal, Litany of the saints · The Imitation of Christ, 1, 23, 1 · St. Francis of Assisi Canticle of the Creatures