1 Corinthians 14:22-24

22Speaking in tongues, then, is intended as a sign, not for believers but for unbelievers, while prophecy is not for unbelievers but for believers.

23If, therefore, the whole church assembles together and all are speaking in tongues and people who are outsiders or unbelievers come in, will they not say that you are out of your minds?

24But if all are prophesying and some unbeliever or outsider comes in, he is convicted by all and is called to account by all.