1 Corinthians 14:10-15

There are, perhaps, a great many kinds of languages in the world, and no kind is without meaning. If then I do not know the meaning of the language, I will be to the one who speaks a barbarian, and the one who speaks will be a barbarian to me. So also you, since you are zealous of spiritual gifts, seek to abound for the edification of the church. Therefore let one who speaks in a tongue pray that he may interpret. For if I pray in a tongue, my spirit prays, but my mind is unfruitful. What is the outcome then? I will pray with the spirit and I will pray with the mind also; I will sing with the spirit and I will sing with the mind also.