1 Corinthians 14:22-24

22So you see that speaking in tongues is a sign, not for believers, but for unbelievers. Prophecy, however, is for the benefit of believers, not unbelievers.

23Even so, if unbelievers or people who don’t understand these things come into your church meeting and hear everyone speaking in an unknown language, they will think you are crazy.

24But if all of you are prophesying, and unbelievers or people who don’t understand these things come into your meeting, they will be convicted of sin and judged by what you say.