"[In copies of the Book of Hours,] one also finds eccentric little texts like the verses of St Bernard, sometimes preceded by an anecdote explaining their origin. One day (the rubrics in the Book of hours tell us) the Devil appeared to St Bernard and boasted that he knew of seven special verses in the Psalms so efficacious that whoever recited them daily could not die in sin. Ste Bernard cried, 'What are they? Tell me at once!' 'I shan't,' said the Devil, 'You shall not know them.' St Bernard then replied that he would have the recite the entire Psalter every day in order to be sure of including the seven magic verses, and the Devil, fearing that this excessive devotion would do too much good, quickly revealed the verses."
- Christopher de Hamel, A History of Illuminated Manuscripts, 176.