Christopher de Hamel:
One also finds [in a Book of Hours] 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 [or eight] special verses in the Psalms so efficacious that whoever recited them daily could not die in sin. St. 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 to 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.[A History of Illuminated Manuscripts by Christopher de Hamel. Phaidon: London, 1994]
The verses are:
Illumina oculos meos ... adversus eum. [Ps. 12:4-5]
In manus tuas Domine ... Deus veritatis. [Ps. 30:6]
Locutus sum in lingua mea ... finem meum. [Ps. 38:5]
Et numerum dierum meorum ... desit mihi. [Ps. 38:5]
Disrupisti Domine Vincula mea ... invocabo. [Ps. 115:16-17]
Periit fuga a me ... animam meam. [Ps. 141:5]
Clamavi ad te Domine ... terra vivencium. [Ps. 141:6]
Fac mecum signum ... consolatus es me. [Ps. 85:17]