1 Corinthians 14:7-9

New Matthew Bible

⁷ Moreover, when things without life give sound, whether it be a pipe or a harp, unless they make a distinction in the sounds, how can it be known what is piped or harped? ⁸ And also, if the trumpet gives an uncertain call, who will prepare himself to fight? 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.