1 Corinthians 14:4

He that speaketh in an unknown tongue edifieth himself; knowledge or understanding of the things that any man speaketh, is necessary to the improvement of them, by their being a means to promote faith and love; for how shall what men say in the least promote, either my faith in God or Christ, or my love to him, if I understand not what they say? How shall they believe in him of whom they have not heard? Romans 10:14. So that, though he that speaketh in an unknown tongue may (if he understand what he says) have his own heart affected with what he saith, yet it is not possible he should affect another. But he that prophesieth edifieth the church; but he that preacheth in an intelligible language and style to all that hear him, he doth what in him lieth to edify all those that hear him.