For he that speaketh in another [1] 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." [2] In the use of the word tongue, there is not a pleonasm, [3] 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."

Footnotes

1 - It is remarked by Granville Penn, that "the context shows that the Apostle means, a language foreign to that of the auditors, and, therefore, not known to them" -- as "we learn from verse 21 that we are to supply hetera -- other,' not agnostHu -- unknown.' We have," he adds, "had lamentable proof of the abuse to which the latter injudicious rendering can be perverted in the hands of ignorant or insidious enthusiasm, by assuming the term to mean, a tongue unknown to all mankind;' and from thence, by an impious inference, supernatural and divine; instead of relatively, unknown to another people.' And yet, after all, unknown' is not the Apostle's word, but only an Italic supplement suggested by the English revisers of the seventeenth century." -- Ed

2 - "Comme on dit en prouerbe -- I1 presche a soy-mesme et aux murailles;" -- "As they say proverbially -- He preaches to himself and the bare walls." The proverb, "Sibi canit et Musis" -- ("He sings to himself and the Muses,") is believed to have originated in a saying of Antigenides, a celebrated musician of Thebes, who, when his scholar Ismenias sung with good taste, but not so as to gain the applause of the people, exclaimed -- "Mihi cane et Musis;" -- ("Sing to me and the Muses") -- meaning that it was enough, if he pleased good judges. -- Ed.

3 - A pleonasm is a figure of speech -- involving a redundancy of expression. -- Ed.

For he that speaketh in an unknown tongue - This verse is designed to show that the faculty of speaking intelligibly, and to the edification of the church, is of more value than the power of speaking a foreign language. The reason is, that however valuable may be the endowment in itself, and however important the truth which he may utter, yet it is as if he spoke to God only. No one could understand him.
Speaketh not unto men - Does not speak so that people can understand him. His address is really not made to people, that is, to the church. He might have this faculty without being able to speak to the edification of the church. It is possible that the power of speaking foreign languages and of prophesying were sometimes united in the same person; but it is evident that the apostle speaks of them as different endowments, and they probably were found usually in different individuals.
But unto God - It is as if he spoke to God. No one could understand him but God. This must evidently refer to the addresses "in the church," when Christians only were present, or when those only were present who spoke the same language, and who were unacquainted with foreign tongues. Paul says that "there" that faculty would be valueless compared with the power of speaking in a manner that should edify the church. He did not undervalue the power of speaking foreign languages when foreigners were present, or when they went to preach to foreigners; see 1-Corinthians 14:22. It was only when it was needless, when all present spoke one language, that he speaks of it as of comparatively little value.
For no man understandeth him - That is, no man in the church, since they all spoke the same language, and that language was different from what was spoken by him who was endowed with the gift of tongues. As God only could know the import of what he said, it would be lost upon the church, and would be useless.
Howbeit in the Spirit - Although, by the aid of the Spirit, he should, in fact, deliver the most important and sublime truths. This would doubtless be the case, that those who were thus endowed would deliver most important truths, but they would be "lost" upon those who heard them, because they could not understand them. The phrase "in the Spirit," evidently means "by the Holy Spirit," that is, by his aid and influence. Though he should be "really" under the influence of the Holy Spirit, and though the important truth which he delivers should be imparted by his aid, yet all would be valueless unless it were understood by the church.
He speaketh mysteries - For the meaning of the word "mystery," see Note, 1-Corinthians 2:7. The word here seems to be synonymous with sublime and elevated truth; truth that was not before known, and that might be of the utmost importance.

For he that speaketh in an unknown tongue - This chapter is crowded with difficulties. It is not likely that the Holy Spirit should, in the church, suddenly inspire a man with the knowledge of some foreign language, which none in the church understood but himself; and lead him to treat the mysteries of Christianity in that language, though none in the place could profit by his teaching.
Dr. Lightfoot's mode of reconciling these difficulties is the most likely I have met with. He supposes that by the unknown tongue the Hebrew is meant, and that God restored the true knowledge of this language when he gave the apostles the gift of tongues. As the Scriptures of the Old Testament were contained in this language, and it has beauties, energies, and depths in it which no verbal translation can reach, it was necessary, for the proper elucidation of the prophecies concerning the Messiah, and the establishment of the Christian religion, that the full meaning of the words of this sacred language should be properly understood. And it is possible that the Hebrew Scriptures were sometimes read in the Christian congregations as they were in the Jewish synagogues; and if the person who read and understood them had not the power and faculty of explaining them to others, in vain did he read and understand them himself. And we know that it is possible for a man to understand a language, the force, phraseology, and idioms of which he is incapable of explaining even in his mother tongue. We shall see, in the course of these notes, how this view of the subject will apply to the illustration of the apostle's words throughout the chapter.
Speaketh not unto men, but unto God - None present understanding the language, God alone knowing the truth and import of what he says: -
In the spirit he speaketh mysteries - Though his own mind (for so πνευματι is understood here by many eminent critics) apprehends the mysteries contained in the words which he reads or utters; but if, by the spirit, we understand the Spirit of God, it only shows that it is by that Spirit that he is enabled to speak and apprehend these mysteries. See the note on 1-Corinthians 14:19.

(2) For he that speaketh in an [unknown] (b) tongue speaketh not unto men, but unto God: for no man understandeth [him]; howbeit in the (c) spirit he speaketh mysteries.
(2) He reprehends their perverse judgment concerning the gift of tongues. For why was it given? The answer: so that the mysteries of God might be the better known to a greater number. By this it is evident that prophecy, which the gift of tongues ought to serve, is better than this: and therefore the Corinthians judged incorrectly, in that they made more account of the gift of tongues than of prophesying: because no doubt the gift of tongues was a thing more to be bragged of. And hereupon followed another abuse of the gift of tongues, in that the Corinthians used tongues in the congregation without an interpreter. And although this thing might be done to some profit of him that spoke them, yet he corrupted the right use of that gift because there came by it no profit to the hearers. And common assemblies were instituted and appointed not for any private man's commodity, but for the profit of the whole company.
(b) A strange language, which no man can understand without an interpreter.
(c) By that inspiration which he has received of the Spirit, which nonetheless he abuses, when he speaks mysteries which none of the company can understand.

For he that speaketh in an unknown tongue,.... Or with tongues, as some copies and the Ethiopic version read: Dr. Lightfoot thinks, that the Hebrew tongue, which was become a dead language, and understood but by few, is here meant, and that not without reason; seeing the public prayers, preaching, and singing of psalms among the Jews, were in this languages (x); in imitation of whom, such ministers, who had the gift of speaking this language, read the Scriptures, preached, prayed, and sung psalms in it, which were no ways to the edification of the people, who understood it not; upon which account the apostle recommends prophesying, praying, and singing, in a language that was understood: otherwise he
speaketh not unto men; to the understanding, profit, and edification of men: but unto God: to his praise and glory, and he only knowing, who knows all languages, and every word in the tongue what is said; excepting himself, unless there should be any present capable of interpreting:
for no man understandeth him: or "heareth him": that is, hears him, so as to understand him; he may hear a sound, but he cannot tell the meaning of it, and so it is of no use and advantage to him:
howbeit in the Spirit he speaketh mysteries; though under the influence and by the extraordinary gift of the Spirit he has, and to his own Spirit and understanding, and with great affection and devotion within himself, he speaks of the deep things of God, and the mysteries of his grace, the most glorious truths of the Gospel, yet the meaning of his voice and words not being known, he is a barbarian to them that hear him; and though what he delivers are truths of the greatest importance, they are a mere jargon to others, being unintelligible.
(x) Vid. Gloss. in T. Bab. Beracot, fol. 3. 1. & in Yoma, fol. 20. 2.

speaketh . . . unto God--who alone understands all languages.
no man understandeth--generally speaking; the few who have the gift of interpreting tongues are the exception.
in the spirit--as opposed to "the understanding" (1-Corinthians 14:14).
mysteries--unintelligible to the hearers, exciting their wonder, rather than instructing them. Corinth, being a mart resorted to by merchants from Asia, Africa, and Europe, would give scope amidst its mixed population for the exercise of the gift of tongues; but its legitimate use was in an audience understanding the tongue of the speaker, not, as the Corinthians abused it, in mere display.

He that speaketh in an unknown tongue speaks, in effect, not to men, but to God - Who alone understands him.