When we recite the Psalter, we promise God:
I will meditate upon your statutes, and will not forget your words. It is a salutary thing for all Christians to observe this, but it is especially incumbent upon those who have received the sacerdotal dignity. Therefore we decree, that every one who is raised to the rank of the episcopate shall know the Psalter by heart, so that from it he may admonish and instruct all the clergy who are subject to him. And diligent examination shall be made by the metropolitan whether he be zealously inclined to read diligently, and not merely now and then, the sacred canons, the Holy Gospel, and the book of the divine Apostle, and all other divine Scripture; and whether he lives according to God’s commandments, and also teaches the same to his people. For the special treasure of our high priesthood is the oracles which have been divinely delivered to us, that is the true science of the Divine Scriptures, as says Dionysius the Great. And if his mind be not set, and even glad, so to do and teach, let him not be ordained. For says God by the prophet,
You have rejected knowledge, I will also reject you, that you shall be no priest to me.
Ancient Epitome: Whoever is to be a bishop must know the Psalter by heart: he must thoroughly understand what he reads, and not merely superficially, but with diligent care, that is to say the Sacred Canons, the Holy Gospel, the book of the Apostle, and the whole of the Divine Scripture. And should he not have such knowledge, he is not to be ordained. (Canon 2)