John Chrysostom, on 1Cor 14:6

"But now, brethren, if I come unto you speaking with tongues, what shall I profit you, unless I speak to you either by way of revelation, or of knowledge, or of prophesying, or of teaching?"

"And why speak I," saith he, "of the rest? Nay, let the person who speaketh with tongues be Paul: for not even so will any good come to the hearers" And these things he saith to signify that he is seeking their profit, not beating any grudge against them that have the gift; since not even in his own person doth he shrink from pointing out its unprofitableness. And indeed it is his constant way to work out the disagreeable topics in his own person: as in the beginning of the Epistle he said, "Who then is Paul? and who is Apollos? and who is Cephas?" This same then he doth also here, saying, "Not even I shall profit you, except I speak to you either by way of revelation, or of prophesying, or of knowledge, or of teaching." And what he means is, "if I say not somewhat that can be made intelligible to you and that may be dear, but merely make display of my having the gift of tongues;-tongues which ye do not understand, ye will go away with no sort of profit. For how should you profit by a voice which ye understand not?"