1 Corinthians 14:14

For if I pray in an unknown tongue ,.... In the Hebrew tongue, which the greatest part of the Jewish doctors insisted F1 Vid. Trigland. de Sect. Kar. c. 10. p. 172,173. upon should be only used in prayer; which notion might be borrowed from them, and now greatly prevailed in the church at Corinth; and the custom was used by such as had the gift of speaking that language, even though the body and bulk of the people understood it not:

my spirit prayeth ; I pray with my breath vocally; or else with affection and devotion, understanding what I say myself, and so am edified; or rather with the gift of the Spirit bestowed on me:

but my understanding is unfruitful ; that is, what I say with understanding to myself is unprofitable to others, not being understood by them.