1 Corinthians 14:18-22

I thank God, I speak in tongues more than you all;

nevertheless, in church I prefer to speak five words with my mind so that I may instruct others also, rather than ten thousand words in a tongue. Instruction for the Church

Brothers and sisters, do not be children in your thinking; yet in evil be infants, but in your thinking be mature.

In the Law it is written: “By men of strange tongues and by the lips of strangers I will speak to this people, and even so they will not listen to Me,” says the Lord.

So then, tongues are for a sign, not to those who believe but to unbelievers; but prophecy is not for unbelievers, but for those who believe.