Chapter 33 — Part IV: Prayer — On Prayer in General
Section 91. But though (our Lord) prohibits loquacity, He is so far from forbidding continuance in prayer which proceeds from the eager and prolonged devotion of the soul that by His own example He exhorts us to such prayer. Not only did He spend whole nights in prayer, but also prayed the third time, saying the self-same words. The inference, therefore, to be drawn from the prohibition is that prayers consisting of mere empty sounds are not to be addressed to God.