1 Corinthians 14:9-11

New Matthew Bible

⁹ So also likewise, when you speak with tongues, unless you speak words that have meaning, how can it be understood what is spoken? For you will be but speaking in the air.

¹⁰ Many kinds of voices are in the world, and none of them are without signification. ¹¹ If I do not know what the voice means, I will be as a foreigner to him who speaks, and he who speaks will be a foreigner to me.