1 Corinthians 14:9-11

9So you too, unless you produce intelligible speech by the tongue, how will it be known what is spoken? For you will just be 1talking to the air.

10There are, perhaps, a great many kinds of 2languages in the world, and none is incapable of meaning.

11So if I do not know the meaning of the language, I will be 3unintelligible to the one who speaks, and the one who speaks will be unintelligible 4to me.