John Chrysostom, on 1Cor 14:27

"And if any man speaketh in a tongue, let it be by two, or at the most by three, and that in turn; and let one interpret. But if there be no interpreter, let him keep silence in the Church; and let him speak to himself, and to God."

What sayest thou, tell me? Having spoken so much of tongues, that the gift is a thing unprofitable, a thing superfluous, if it have no interpreter, dost thou command again to speak with tongues? I do not command, saith he, neither do I forbid; as when he saith, "if any of them that believe not bid you to a feast and ye be disposed to go," he saith it not laying down a law for them to go, but not hindering them: so likewise here. "And let him speak. to himself and to God." If he endure not to be silent, saith he, but is so ambitious and vain-glorious, "let him speak by himself." And thus, by the very fact of so permitting, he greatly checked and put them to shame. Which he doth also elsewhere, discoursing of converse with a wife and saying, "But this I say because of your incontinency." But not so did he speak, when he was discoursing of prophecy. How then? In a tone of command and legislation: "Let the prophets speak, two or three." And he no where here seeks the interpreter, nor doth he stop the mouth of him that prophesies as under the former head, saying, "If there be no interpreter, let him keep silence;" because in fact he who speaks in a tongue is not sufficient of himself. Wherefore if any hath both gifts, let him speak. But if he hath not, yet wish to speak, let him do so with the interpreter's aid. For the prophet is an interpreter, but of God; whereas thou art of man. "But if there be no interpreter, let him keep silence:" for nothing ought to be done superfluously, nothing for ambition. Only "let him speak to himself and to God;" i.e., mentally, or quietly and without noise: at least, if he will speak. For this is surely not the tone of one making a law, but it may be of one who shames them more even by his permission; as when he saith, "but if any hunger, let him eat at home:" and seeming to give permission, he touches them hereby the more sharply. "For ye come not together for this purpose," saith he, "that ye may show that ye have a gift, but that ye may edify the hearers;" which also he before said, "Let all things be done unto edifying."