Genesis 11:7

And they were all filled with the Holy Spirit and began to speak in other tongues, as the Spirit gave them utterance.

For one who speaks in a tongue does not speak to men but to God; for no one understands him, but in his spirit he speaks mysteries.

Therefore if the whole church assembles together and all speak in tongues, and outsiders or unbelievers enter, will they not say that you are mad?

Treasury of Scripture Knowledge

Go to, let us go down, and there confound their language, that they may not understand one another's speech.

And they were all filled with the Holy Spirit and began to speak in other tongues, as the Spirit gave them utterance.

For one who speaks in a tongue does not speak to men but to God; for no one understands him, but in his spirit he speaks mysteries.