This is the fourth responsory of the first nocturn for the Matins of the feast of St Bernard on 20 August. Its quite a nice work with in a very low tessitura, which gives the text In timore Dei a whole solemn character, which is also enhanced by Mode 1.
Two years ago, in September 2013 I had the opportunity of presenting a paper on these responsories at the “I Residência Cisterciense S. Bento de Cástris: O Silêncio” held at the cistercian nun monastery of S. Bento de Cástris, near Évora. The paper was about a cistercian antiphonary – P-AR Ms 25 – from another nun Portuguese monastery in Arouca. This responsory was one of the musical examples I transcribed and sung during the presentation, together with other two responsories: O odoriferum lilium (first responsory of the second nocturn) and O oliva fructifera (first responsory of the third nocturn).
These responsories are also to be found in one of the chant sources from the monastery of S. Bento de Cástris, more specifically a sixteenth-century Sanctorale antiphonary P-EVad Ms 35, now preserved at Évora Districtal Archive.