Charles Ellicott Commentary 1 Corinthians 14:15

"What is it then? I will pray with the spirit, and I will pray with the understanding also: I will sing with the spirit, and I will sing with the understanding also." — 1 Corinthians 14:15 (ASV)

What is it then?—The Apostle, in answering this question—namely, What, then, is the practical conclusion of the whole matter?—still speaks in the first person, quoting his own conduct and resolution. He will not let his public ministrations regarding prayer and praise evaporate into mere enthusiasm; nor will he, on the other hand, allow a cold intellectual creed to chill and freeze the warm emotions of the spirit.