1 Corinthians 14:6-12
14:6 Now, brothers and sisters, if I come to you speaking in tongues, how will I help you unless I speak to you with a revelation or with knowledge or prophecy or teaching?
14:7 It is similar for lifeless things that make a sound, like a flute or harp. Unless they make a distinction in the notes, how can what is played on the flute or harp be understood?
14:8 If, for example, the trumpet makes an unclear sound, who will get ready for battle?
14:9 It is the same for you. If you do not speak clearly with your tongue, how will anyone know what is being said? For you will be speaking into the air.
14:10 There are probably many kinds of languages in the world, and none is without meaning.
14:11 If then I do not know the meaning of a language, I will be a foreigner to the speaker and the speaker a foreigner to me.
14:12 It is the same with you. Since you are eager for manifestations of the Spirit, seek to abound in order to strengthen the church.