1 Corinthians 14:10-15

There are, it may be, so many kinds of voices in the world, and no kind is without signification. If then I know not the meaning of the voice, I shall be to him that speaketh a barbarian, and he that speaketh will be a barbarian unto me. So also ye, since ye are zealous of spiritual gifts, seek that ye may abound unto the edifying of the church. Wherefore let him that speaketh in a tongue pray that he may interpret. For if I pray in a tongue, my spirit prayeth, but my understanding is unfruitful. What is it then? I will pray with the spirit, and I will pray with the understanding also: I will sing with the spirit, and I will sing with the understanding also.