1 Corinthians 14:21-23
21
In the Law it is written:
“Through men of strange tongues
and through the lips of foreigners
I will speak to this people,
but even then they will not listen to me,”
says the Lord.
22 Tongues, then, are a sign, not for believers but for unbelievers; prophecy, however, is for believers, not for unbelievers.
23 So if the whole church comes together and everyone speaks in tongues, and some who do not understand or some unbelievers come in, will they not say that you are out of your mind?