1 Corinthians 14:8-10

Darby Translation

⁸ For also, if the trumpet give an uncertain sound, who shall prepare himself for war?

⁹ Thus also *ye* with the tongue, unless ye give a distinct speech, how shall it be known what is spoken? for ye will be speaking to the air.

¹⁰ There are, it may be, so many kinds of voices in the world, and none of undistinguishable sound.