The Most Ancient Lives of Saint Patrick/The Life and Acts of St. Patrick/Chapter 72
Of the Sentence pronounced on Murinus.
And the saint having blessed and bidden farewell unto the inhabitants of Dublinia, then by the power of his miracles confirmed in the faith, preparing himself for the like work, set forward on his journey. And he came unto a neighboring town, which is now called the Castle Cnoc, where a certain infidel named Murinus governed. Him did the saint desire to lead into the path of life; but this son of death, hearing the fame of his virtue and of his wisdom, which he feared no one could resist, absented himself from the saint, even as from a fierce enemy. And the saint required him that he would at the least give unto him of his abundance; but he, concealing himself in an inner chamber, required him that he would at the least suffer him to sleep. The which commands being of each oftentimes repeated, the saint, at the inspiration of the Spirit, understanding him to be a child of perdition, exclaimed: "Let him sleep, let him sleep; nor until the day of judgment let him awaken or arise!" Then the saint departed, and the wretched man sank into the sleep of death. Thus when the sleeper, covered with the darkness of unbelief, refused to awake at the heavenly voice which called him from the dead, that he might be illuminated of Christ, he descended into the dark grave, there to remain for ever covered with the darkness of death. Therefore, even to this day, it is among the Irish a frequent imprecation on a feigned sleeper, Mayest thou sleep, as at the word of Saint Patrick Murinus slept!