"11 [VIII, ix]
Those who have learned to say the canonical hours with the clerics should do so according to
the practice of the holy Fathers and the approved custom of the Church. Those who do not
know the hours are to say the Our Father twenty-five times for the night office—except for
Sunday and solemn feasts when this number is doubled, so that the Our Father is said fifty
times. It is to said seven times for the morning Lauds and for the other Hours, except for
Vespers when it must be said fifteen times."