Catechism of the Catholic Church §647 — excerpt
O truly blessed Night, sings the Exsultet of the Easter Vigil, which alone deserved to know the time and the hour when Christ rose from the realm of the dead!
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: O vere beata nox, quae sola meruit scire tempus · horam, in qua Christus ab inferis resurrexit!