4 He that speaks with a tongue edifies himself; but he that prophesies edifies [the] assembly. 5 Now I desire that ye should all speak with tongues, but rather that ye should prophesy. But greater is he that prophesies than he that speaks with tongues, unless he interpret, that the assembly may receive edification.

6 And now, brethren, if I come to you speaking with tongues, what shall I profit you, unless I shall speak to you either in revelation, or in knowledge, or in prophecy, or in teaching? 7 Even lifeless things giving a sound, whether pipe or harp, if they give not distinction to the sounds, how shall it be known what is piped or harped? 8 For also, if the trumpet give an uncertain sound, who shall prepare himself for war?

Matthew Henry's Commentary on 1 Corinthians 14:4-8

Commentary on 1 Corinthians 14:1-5

(Read 1 Corinthians 14:1-5)

Prophesying, that is, explaining Scripture, is compared with speaking with tongues. This drew attention, more than the plain interpretation of Scripture; it gratified pride more, but promoted the purposes of Christian charity less; it would not equally do good to the souls of men. What cannot be understood, never can edify. No advantage can be reaped from the most excellent discourses, if delivered in language such as the hearers cannot speak or understand. Every ability or possession is valuable in proportion to its usefulness. Even fervent, spiritual affection must be governed by the exercise of the understanding, else men will disgrace the truths they profess to promote.

Commentary on 1 Corinthians 14:6-14

(Read 1 Corinthians 14:6-14)

Even an apostle could not edify, unless he spoke so as to be understood by his hearers. To speak words that have no meaning to those who hear them, is but speaking into the air. That cannot answer the end of speaking, which has no meaning; in this case, speaker and hearers are barbarians to each other. All religious services should be so performed in Christian assemblies, that all may join in, and profit by them. Language plain and easy to be understood, is the most proper for public worship, and other religious exercises. Every true follower of Christ will rather desire to do good to others, than to get a name for learning or fine speaking.