1 Corinthians 14:2
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. 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.
The verse distinguishes genuine speaking in tongues from meaningless gibberish claimed as a spiritual gift, for genuine tongues are not unintelligible gibberish. Speech that no one understands is not a gift God has placed in the church. Speech that is unintelligible not only to people but also to God and heaven is counterfeit. Merely calling such unintelligible speech an unknown tongue does not make it one. Its noisy excitement and bad fruits expose it as false.