1 Corinthians 14:9-11 Common English Bible (CEB)
9 It’s the same way with you: If you don’t use language that is easy to understand when you speak in a tongue, then how will anyone understand what is said? 10 It will be as if you are speaking into the air! There are probably many language families in the world, and none of them are without meaning. 11 So if I don’t know the meaning of the language, then I will be like a foreigner to those who speak it, and they will be like foreigners to me.