1 Corinthians 14:7 (KJV)

For he that speaketh in an unknown tongue speaketh not unto men, but unto God: for no man understandeth him; howbeit in the spirit he speaketh mysteries.

But he that prophesieth speaketh unto men to edification, and exhortation, and comfort.

He that speaketh in an unknown tongue edifieth himself; but he that prophesieth edifieth the church.

I would that ye all spake with tongues but rather that ye prophesied: for greater is he that prophesieth than he that speaketh with tongues, except he interpret, that the church may receive edifying.

Now, brethren, if I come unto you speaking with tongues, what shall I profit you, except I shall speak to you either by revelation, or by knowledge, or by prophesying, or by doctrine?

For if the trumpet give an uncertain sound, who shall prepare himself to the battle?

So likewise ye, except ye utter by the tongue words easy to be understood, how shall it be known what is spoken? for ye shall speak into the air.

There are, it may be, so many kinds of voices in the world, and none of them is without signification.

Therefore if I know not the meaning of the voice, I shall be unto him that speaketh a barbarian, and he that speaketh shall be a barbarian unto me.

Even so ye, forasmuch as ye are zealous of spiritual gifts, seek that ye may excel to the edifying of the church.