1 CORINTHIANS CHAPTER 14.
The Use of Spiritual Gifts in Public Worship. 1 Cor. 14, 1-40.
Only through the understanding of the hearer does the utterance of the Spirit result in edification: V. 14. For if I pray in an unknown tongue, my spirit prayeth, but my understanding is unfruitful. V. 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.
Since the purpose of every function in public worship is to be of spiritual benefit to the attendants, therefore the gift of tongues must be considered of secondary value: For if I pray with a tongue, my spirit prays, but my understanding is without fruit.
As one commentator has it: The fruit of the speaker is found in the profit of the hearer. If a man got up in public service in Corinth and prayed with the ecstatic utterance of this peculiar gift, his own spirit indeed had the benefit of feeling itself the instrument of the Holy Ghost, but all the other people present had no benefit whatsoever from his praying, because there was no point of contact between them, they could not understand the speaker, unless, indeed, he also interpreted his utterances.
This being the case, what follows? The apostle writes: I will pray with the spirit, but I will pray also with the understanding, with the mind; I will sing psalms with the spirit, but I will sing psalms also with the understanding, with the mind.
The wonderful utterances which were given to the apostle to articulate he wanted to make accessible also to his hearers, whether they were in the form of prayer or in that of chants, and to do this, it was necessary that he bring out the content of the speaking with tongues in the form of common speech. The hearer's mind and heart could not be reached without interpretation, and without that there could be no edification.