1 Corinthians 14:14

For if I pray in a tongue, my spirit prayeth, but my understanding is unfruitful.

As Lipscomb said with reference to this and 1 Corinthians 14:15:

Neither the KJV nor the English Revised Version (1885) is correct here. The thought evidently is, "I will sing as the Spirit directs or inspires, and I will sing in a language that those who hear can understand."... The following verse shows clearly that Paul's meaning is: "I will pray and sing by the inspiration of the Spirit, and in a language that they will understand to their profit."[6]

The inference that must be made from this and the next verses is that the tongue-speakers had even taken over the songs and prayers of the public worship! Of course, Paul would not countenance anything of that kind.

The quotation of these verses in the sense of people singing and praying in the public services "with the spirit and the understanding" is based upon an incorrect discernment of their meaning. It is not the subjective understanding of the participant that is meant, but the objective purpose of conveying understanding to others.