1 Corinthians 14:16

Else when thou shalt bless with the spirit. — In this and the following verse the Apostle speaks in the second person, for they refer, not to his practice, but to that of some in Corinth. Their conduct and its results are introduced parenthetically here, in contrast with what he is laying down as his own earnest desire and practice.

He that occupieth the room of the unlearned. — Better, he that is in the position of a private individual; as we should say, a “layman” — the one who comes as a private person to the assembly, and does not lead the prayer and thanksgiving. How can he say “Amen” when he does not know what is being said? and he cannot know if you speak in a tongue, without interpreting. It would seem from this verse that from the earliest apostolic times the practice has been for the congregation to join in the thanksgiving by uttering “Amen” (the Hebrew “So be it”) at the conclusion.