1 Corinthians 14:22-24

22Therefore tongues are for a sign, not to those who believe but to unbelievers; but prophesying is not for unbelievers but for those who believe.

23Therefore if the whole church comes together in one place, and all speak with tongues, and there come in those who are uninformed or unbelievers, will they not say that you are out of your mind?

24But if all prophesy, and an unbeliever or an uninformed person comes in, he is convinced by all, he is convicted by all.