1 Corinthians 14:2-15

For anyone who speaks in a tongue does not speak to people but to God. Indeed, no-one understands them; they utter mysteries by the Spirit. But the one who prophesies speaks to people for their strengthening, encouraging and comfort. Anyone who speaks in a tongue edifies themselves, but the one who prophesies edifies the church. I would like every one of you to speak in tongues, but even more to prophesy. The one who prophesies is greater than the one who speaks in tongues, unless someone interprets, so that the church may be edified. Now, brothers and sisters, if I come to you and speak in tongues, what good will I be to you, unless I bring you some revelation or knowledge or prophecy or word of instruction? Even in the case of lifeless things that make sounds, such as the pipe or harp, how will anyone know what tune is being played unless there is a distinction in the notes? Again, if the trumpet does not sound a clear call, who will get ready for battle? So it is with you. Unless you speak intelligible words with your tongue, how will anyone know what you are saying? You will just be speaking into the air. Undoubtedly there are all sorts of languages in the world, yet none of them is without meaning. If then I do not grasp the meaning of what someone is saying, I am a foreigner to the speaker, and the speaker is a foreigner to me. So it is with you. Since you are eager for gifts of the Spirit, try to excel in those that build up the church. For this reason the one who speaks in a tongue should pray that they may interpret what they say. For if I pray in a tongue, my spirit prays, but my mind is unfruitful. So what shall I do? I will pray with my spirit, but I will also pray with my understanding; I will sing with my spirit, but I will also sing with my understanding.