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.
Matthew Henry's Commentary on 1 Corinthians 14:9-12
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.