9 Thus also ye with the tongue, unless ye give a distinct speech, how shall it be known what is spoken? for ye will be speaking to the air. 10 There are, it may be, so many kinds of voices in the world, and none of undistinguishable sound. 11 If therefore I do not know the power of the sound, I shall be to him that speaks a barbarian, and he that speaks a barbarian for me. 12 Thus ye also, since ye are desirous of spirits, seek that ye may abound for the edification of the assembly. 13 Wherefore let him that speaks with a tongue pray that he may interpret. 14 For if I pray with a tongue, my spirit prays, but my understanding is unfruitful.
15 What is it then? I will pray with the spirit, but I will pray also with the understanding; I will sing with the spirit, but I will sing also with the understanding. 16 Since otherwise, if thou blessest with [the] spirit, how shall he who fills the place of the simple [Christian] say Amen, at thy giving of thanks, since he does not know what thou sayest? 17 For thou indeed givest thanks well, but the other is not edified. 18 I thank God I speak in a tongue more than all of you: 19 but in [the] assembly I desire to speak five words with my understanding, that I may instruct others also, [rather] than ten thousand words in a tongue.
Matthew Henry's Commentary on 1 Corinthians 14:9-19
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.
Commentary on 1 Corinthians 14:15-25
(Read 1 Corinthians 14:15-25)
There can be no assent to prayers that are not understood. A truly Christian minister will seek much more to do spiritual good to men's souls, than to get the greatest applause to himself. This is proving himself the servant of Christ. Children are apt to be struck with novelty; but do not act like them. Christians should be like children, void of guile and malice; yet they should not be unskilful as to the word of righteousness, but only as to the arts of mischief. It is a proof that a people are forsaken of God, when he gives them up to the rule of those who teach them to worship in another language. They can never be benefitted by such teaching. Yet thus the preachers did who delivered their instructions in an unknown tongue. Would it not make Christianity ridiculous to a heathen, to hear the ministers pray or preach in a language which neither he nor the assembly understood? But if those who minister, plainly interpret Scripture, or preach the great truths and rules of the gospel, a heathen or unlearned person might become a convert to Christianity. His conscience might be touched, the secrets of his heart might be revealed to him, and so he might be brought to confess his guilt, and to own that God was present in the assembly. Scripture truth, plainly and duly taught, has a wonderful power to awaken the conscience and touch the heart.