Adam Clarke on 1 Corinthians 14:27

Speak in an unknown tongue - The Hebrew, as has already been conjectured.

Let it be by two; or at the most by three, and that by course - Let only two or three in one assembly act in this way, that too much time may not be taken up with one exercise; and let this be done by course, the one after the other, that two may not be speaking at the same time: and let one interpret for all that shall thus speak.