A.T. Robertson Commentary 1 Corinthians 14:29

"And let the prophets speak [by] two or three, and let the others discern." — 1 Corinthians 14:29 (ASV)

By two or three (δυο η τρεις). No κατα here as in verse 27. Let two or three prophets speak.

Let the others discern (ο αλλο διακρινετωσαν). Whether what is said is really of the Spirit. Cf. 12:10 διακρισεις πνευματων.