1 Corinthians 14:4, 17
1 Corinthians 14:4 AMP
One who speaks in a tongue edifies himself; but one who prophesies edifies the church [promotes growth in spiritual wisdom, devotion, holiness, and joy].
1 Corinthians 14:17 AMP
You are giving thanks well enough [in a way that God is glorified], but the other person [who does not understand you] is not edified [and spiritually strengthened since he cannot join in your thanksgiving].