The Holy Rule
In What Order the Psalms Are to Be Said
In the beginning let there be said the verse, Deus, in adjutorium meum intende; Domine, ad adjuvandum me festina (Ps 69:2), and the Gloria, followed by the hymn for each Hour. At Prime on Sunday, then, there are to be said four sections of the 118th psalm. At the other Hours, however, namely Tierce, Sext, and None, let three sections of the same psalm be said. But at Prime on Monday let three psalms be said, namely, the first, the second, and the sixth; and thus each day at Prime until Sunday, let three psalms be said each time in consecutive order up to the 19th psalm, yet so that the ninth psalm and the 17th be each divided into two Glorias; and thus it will come about that at the night office on Sundays we always begin with the 20th psalm.
At Tierce, Sext, and None, on Monday, however, let the nine sections which remain over the 118th psalm be said, three sections at each of these Hours. The 118th psalm having thus been parceled out for two days, namely, Sunday and Monday, let there be sung on Tuesday for Tierce, Sext, and None, three psalms each, from the 119th to the 127th, that is, nine psalms. These psalms will always be repeated at the same Hours in just the same way until Sunday, observing also for all these days a regular succession of the hymns, the lessons, and the verses, so, namely, that on Sunday the beginning is always made with the 118th psalm.
Let Vespers be sung daily with the singing of four psalms. Let these psalms begin with the 109th to the 147th, excepting those which are set aside for the other Hours; namely, from the 117th to the 127th, and the 133d, and the 142d. All the rest are to be said at Vespers; and as the psalms fall three short, those of the aforesaide psalms which are found to be longer, are to be divided; namely, the 138th, the 143d, and the 144th. But because the 116th is short, let it be joined to the 115th. The order of the psalms for Vespers having thus been arranged let the rest, namely, the lessons, the responsories, the hymns, the verses, and the canticles, be said as we have directed above.
At Complin, however, let the same psalms be repeated every day; namely, the 4th, the 90th, and the 133d.
Having arranged the order of the office, let all the rest of the psalms which remain over, be divided equally into seven night offices, by so dividing such of them as are of greater length that twelve fall to each night. We especially impress this, that, if this distribution of the psalms should perchance displease anyone, he arrange them if he thinketh another better, by all means seeing to it that the whole Psalter of one hundred and fifty psalms be said every week, and that it always start again from the beginning at Matins on Sunday; because those monks show too lax a service in their devotion who in the course of a week chant less than the whole Psalter with is customary canticles; since we read, that our holy forefathers promptly fulfilled in one day what we lukewarm monks should, please God, perform at least in a week.