Charles Ellicott Commentary 1 Corinthians 14:29

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

Let the prophets speak.—This is the application of the general principle, Let all be done to edification, to those who had the gift of prophecy. Only two or three prophets are to speak in each assembly on each occasion. The others (not “other,” as in the English version) who had the gift are to sit by, silent and judging, i.e., determining whether the utterances were from the Spirit of God (see 1 Corinthians 12:3 and 1 John 4:1–3).

If, however, while one prophet was speaking, a sudden revelation of truth came to another prophet who was sitting nearby, the speaker would pause, and the other prophet would give utterance to the inspiration which had come to him. The suddenness of the revelation would show that it was a truth needed there and then, and so should find utterance without delay.