[12] So with yourselves, since you are eager for manifestations of the Spirit, strive to excel in building up the church.
[13] Therefore, one who speaks in a tongue should pray that he may interpret. [14] For if I pray in a tongue, my spirit prays but my mind is unfruitful. [15] 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. [16] 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? [17] For you may be giving thanks well enough, but the other person is not being built up. [18] I thank God that I speak in tongues more than all of you. [19] Nevertheless, in church I would rather speak five words with my mind in order to instruct others, than ten thousand words in a tongue.
[20] Brothers, do not be children in your thinking. Be infants in evil, but in your thinking be mature.
(ESV)