1 Corinthians 14:7-11

Yet 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?

For if the trumpet produces an indistinct sound, who will prepare himself for battle?

So 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.

There are, perhaps, a great many kinds of languages in the world, and none is incapable of meaning.

So 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.