Our prayer should be made either in the concealment of our inner room (where without noise and without telling anyone we can pray with a more perfect and pure heart, as he said: When you pray enter your inner room, and having closed the door, pray [Mt. 6:6]); or, if not in one’s room, it should be made in the solitary wilderness, and at the best and most quiet time of night, as he did [Lk. 6:12]. No reason exists, hence, for designating fixed times or set days, or for choosing some days more than others for our devotions; neither is there reason for using other kinds of prayer, or phrases having a play on words, but only those prayers that the Church uses, and as she uses them, for all are reducible to the Pater Noster.
By this I do not condemn — but rather approve — the custom of setting aside certain days for devotions, such as novenas, fasting, and other similar practices. I condemn the fixed methods and ceremonies with which the devotions are carried out, just as Judith reproved the Bethulians for having established a certain time to await God’s mercy: You have fixed a time for God’s mercies. This does not serve to move God to clemency, but to stir up his wrath [Jdt. 8:11-13].
Saint John of the Cross
The Ascent of Mount Carmel, III, ch. 44, nos. 4–5
John of the Cross, St. 1991, The Collected Works of St. John of the Cross, Revised Edition, translated from the Spanish by Kavanaugh, K and Rodriguez, O with revisions and introductions by Kavanaugh, K, ICS Publications, Washington DC.