1 Corinthians 14:2, 4, 15, 39
1 Corinthians 14:2 ESV
For one who speaks in a tongue speaks not to men but to God; for no one understands him, but he utters mysteries in the Spirit.
1 Corinthians 14:4 ESV
The one who speaks in a tongue builds up himself, but the one who prophesies builds up the church.
1 Corinthians 14:15 ESV
What am I to do? I will pray with my spirit, but I will pray with my mind also; I will sing praise with my spirit, but I will sing with my mind also.
1 Corinthians 14:39 ESV
So, my brothers, earnestly desire to prophesy, and do not forbid speaking in tongues.