Albert Barnes 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? What should I do? What is the proper course for me to pursue? What is my practice and my desire? See the same form of expression in Romans 3:9; Romans 6:15. It indicates the conclusion to which the reasoning had led him, or the course he would pursue in view of all the circumstances of the case.

I will pray with the spirit, etc. I will endeavor to blend all the advantages that can be derived from prayer; I will unite all the benefits that can result to myself and to others. I consider it of great importance to pray with the spirit in such a way that the heart and the affections are engaged, so that I may myself benefit from it; but I will also combine with that, usefulness to others; I will use such language that they may understand it and profit.

And I will pray with the understanding also. So that others may understand me. I will make the appropriate use of the intellect, so that it may convey ideas and make suitable impressions on the minds of others.

I will sing with the spirit. It is evident that the same thing could happen in singing that occurred in prayer. It might be in a foreign language and be unintelligible to others. A person's own affections might be stirred, and their heart engaged in the duty, but it would be unprofitable to others. Therefore, Paul says that he would so celebrate the praises of God as to stir the proper affections in his own mind, and so as to be intelligible and profitable to others. This passage proves:

1. That the praises of God are to be celebrated among Christians, and that it is an important part of worship;
2. That the heart should be engaged in it, and that it should be so performed as to stir proper affections in the hearts of those who are engaged in it; and
3. That it should be so done as to be intelligible and edifying to others. The words should be so uttered as to be distinct and understood. There should be clear enunciation, as in prayer and preaching, since the design of sacred music in the worship of God is not only to utter praise but also to impress the sentiments that are sung on the heart, by the aid of musical sounds and expression, more deeply than could otherwise be done.

If this is not done, the singing might as well be in a foreign language. Perhaps there is no part of public worship in which there is greater imperfection than in its mode of psalmody. At the same time, there is scarcely any part of the devotions of the sanctuary that can be made more edifying or impressive. It has the advantage—an advantage that preaching and praying do not have—of using the sweet tones of melody and harmony to impress sentiment on the heart; and it should be done.