Brothers, don’t be children in thoughts, yet in malice be babies, but in thoughts be mature. In the law it is written, “By men of strange languages and by the lips of strangers I will speak to this people. They won’t even listen to me that way, says the Lord.” Therefore other languages are for a sign, not to those who believe, but to the unbelieving; but prophesying is for a sign, not to the unbelieving, but to those who believe. If therefore the whole assembly is assembled together and all speak with other languages, and unlearned or unbelieving people come in, won’t they say that you are crazy? But if all prophesy, and someone unbelieving or unlearned comes in, he is reproved by all, and he is judged by all. And thus the secrets of his heart are revealed. So he will fall down on his face and worship God, declaring that God is among you indeed.

Referring to

Isaiah @isaiah · Isaiah 28:11-13

But he will speak to this nation with stammering lips and in another language, to whom he said, “This is the resting place. Give rest to the weary,” and “This is the refreshing;” yet they would not hear. Therefore the LORD’s word will be to them precept on precept, precept on precept; line on line, line on line; here a little, there a little; that they may go, fall backward, be broken, be snared, and be taken.