1 Corinthians 14:6-11

⁶But now, brothers and sisters, if I come to you speaking in tongues, how will I benefit you unless I speak to you either by way of revelation, or of knowledge, or of prophecy, or of teaching? ⁷Yet even lifeless instruments, whether flute or harp, in producing a sound, if they do not produce a distinction in the tones, how will it be known what is played on the flute or on the harp? ⁸For if the trumpet produces an indistinct sound, who will prepare himself for battle? ⁹So you too, unless you produce intelligible speech by the tongue, how will it be known what is spoken? For you will just be talking to the air. ¹⁰There are, perhaps, a great many kinds of languages in the world, and none is incapable of meaning. ¹¹So if I do not know the meaning of the language, I will be unintelligible to the one who speaks, and the one who speaks will be unintelligible to me.