1 Corinthians 14:13-25 ESV
Therefore, one who speaks in a tongue should pray that he may interpret. For if I pray in a tongue, my spirit prays but my mind is unfruitful. What am I to do? I will pray with my spirit, but I will pray with my mind also; I will sing praise with my spirit, but I will sing with my mind also. Otherwise, if you give thanks with your spirit, how can anyone in the position of an outsider say “Amen” to your thanksgiving when he does not know what you are saying? For you may be giving thanks well enough, but the other person is not being built up. I thank God that I speak in tongues more than all of you. Nevertheless, in church I would rather speak five words with my mind in order to instruct others, than ten thousand words in a tongue.
Brothers, do not be children in your thinking. Be infants in evil, but in your thinking be mature. In the Law it is written, “By people of strange tongues and by the lips of foreigners will I speak to this people, and even then they will not listen to me, says the Lord.” Thus tongues are a sign not for believers but for unbelievers, while prophecy is a sign not for unbelievers but for believers. If, therefore, the whole church comes together and all speak in tongues, and outsiders or unbelievers enter, will they not say that you are out of your minds? But if all prophesy, and an unbeliever or outsider enters, he is convicted by all, he is called to account by all, the secrets of his heart are disclosed, and so, falling on his face, he will worship God and declare that God is really among you.
ESV: English Standard Version 2016