1 Corinthians 14:4-5
4-5The one who prays using a private "prayer language" certainly gets a lot out of it, but proclaiming God's truth to the church in its common language brings the whole church into growth and strength. I want all of you to develop intimacies with God in prayer, but please don't stop with that. Go on and proclaim his clear truth to others. It's more important that everyone have access to the knowledge and love of God in language everyone understands than that you go off and cultivate God's presence in a mysterious prayer language—unless, of course, there is someone who can interpret what you are saying for the benefit of all.
6-8Think, friends: If I come to you and all I do is pray privately to God in a way only he can understand, what are you going to get out of that? If I don't address you plainly with some insight or truth or proclamation or teaching, what help am I to you? If musical instruments—flutes, say, or harps—aren't played so that each note is distinct and in tune, how will anyone be able to catch the melody and enjoy the music? If the trumpet call can't be distinguished, will anyone show up for the battle?