1 Corinthians 14:6-14

6But now, brothers and sisters, if I come to you speaking in tongues, how will I benefit you unless I speak to you either by way of 1revelation, or of 2knowledge, or of 3prophecy, or of 4teaching? 7Yet even lifeless instruments, whether flute or harp, in producing a sound, if they do not produce a distinction in the tones, how will it be known what is played on the flute or on the harp? 8For if 5the trumpet produces an indistinct sound, who will prepare himself for battle? 9So you too, unless you produce intelligible speech by the tongue, how will it be known what is spoken? For you will just be 6talking to the air. 10There are, perhaps, a great many kinds of 7languages in the world, and none is incapable of meaning. 11So if I do not know the meaning of the language, I will be 8unintelligible to the one who speaks, and the one who speaks will be unintelligible 9to me. 12So you too, since you are eager to possess 10spiritual gifts, strive to excel for the 11edification of the church.

13Therefore, one who speaks in a tongue is to pray that he may interpret. 14For if I pray in a tongue, my spirit prays, but my mind is unproductive.