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.
1 Corinthians 14:2
Surrounding context
14:1 Pursue love, and desire spiritual gifts, but especially that you may prophesy.
14:2 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.
14:3 But he who prophesies speaks edification and exhortation and comfort to men.