1 Corinthians 14:14 - Ellicott's Commentary On The Whole Bible

For if I pray in an unknown tongue. — Better, if I pray in a tongue. 1 Corinthians 14:14-19 are expressed in the first person (except 1 Corinthians 14:16-17, which are a parenthesis), as enforcing the Apostle’s own example. A man praying in a tongue needed the gift of interpretation. The emotions of his spirit, kindled by the Spirit of God, found utterance in a “tongue,” the gift of the Spirit of God; but his intellectual faculty grasped no definite idea, and could not, therefore, formulate it into human language; therefore the prayer which is offered merely in a tongue, from the spirit and not from the understanding, is useless as regards others. The Apostle is here speaking of public worship (see 1 Corinthians 14:16), and not of private devotion; and the word “fruitless” implies the result, or rather the absence of result, as regards others.