1 Corinthians 14:9-11

Revised Standard Version

⁹ So with yourselves; if you in a tongue utter speech that is not intelligible, how will any one know what is said? For you will be speaking into the air. ¹⁰ There are doubtless many different languages in the world, and none is without meaning; ¹¹ but if I do not know the meaning of the language, I shall be a foreigner to the speaker and the speaker a foreigner to me.