1 Corinthians 14:9-11

New Revised Standard Version, Anglicised Catholic Edition

⁹ So with yourselves; if in a tongue you utter speech that is not intelligible, how will anyone know what is being said? For you will be speaking into the air. ¹⁰ There are doubtless many different kinds of sounds in the world, and nothing is without sound. ¹¹ If then I do not know the meaning of a sound, I will be a foreigner to the speaker and the speaker a foreigner to me.