1 Corinthians 14:21-23

Amplified Bible

²¹ It is written in the Law, “By men of strange tongues and by the lips of foreigners I will speak to this people, and not even then will they listen to Me,” says the Lord.^{(A) 22} Therefore, [unknown] tongues are [meant] for a [supernatural] sign, not to believers but to unbelievers [who might be receptive]; while prophecy [foretelling the future, speaking a new message from God to the people] is not for unbelievers but for believers. ²³ So then, if the whole church gathers together and all of you speak in [unknown] tongues, and outsiders or those who are not gifted [in spiritual matters] or unbelievers come in, will they not say that you are out of your mind?