1 Corinthians 14:2

2.For he that speaketh in another (808) tongue, speaketh, etc. He now shows from the effect, why it was that he preferred prophecy to other gifts, and he compares it with the gift of tongues, in which it is probable the Corinthians exercised themselves the more, because it had more of show connected with it, for when persons hear a man speaking in a foreign tongue, their admiration is commonly excited. He accordingly shows, from principles already assumed, how perverse a thing this is, inasmuch as it does not at all contribute to the edifying of the Church. He says in the outset — He that speaketh in another tongue, speaketh not unto men, but unto God: that is, according to the proverb, “He sings to himself and to the Muses.” (809) In the use of the word tongue, there is not a pleonasm, (810) as in those expressions — “She spake thus with her mouth,” and “I caught the sound with these ears.” The term denotes a foreign language. The reason why he does not speak to men is — because no one heareth, that is, as an articulate voice. For all hear a sound, but they do not understand what is said.

He speaketh in the Spirit — that is, “by a spiritual gift, (for in this way I interpret it along with Chrysostom.) He speaketh mysteries and hidden things, and things, therefore, that are of no profit.” Chrysostom understands mysteries here in a good sense, as meaning — special revelations from God. I understand the term, however, in a bad sense, as meaning — dark sayings, that are obscure and involved, as if he had said, “He speaks what no one understands.”