I Corinthians 14:2, 14
I Corinthians 14:2 NKJV
For he who speaks in a tongue does not speak to men but to God, for no one understands him; however, in the spirit he speaks mysteries.
I Corinthians 14:14 NKJV
For if I pray in a tongue, my spirit prays, but my understanding is unfruitful.