John Calvin Commentary 1 Corinthians 14:30

"But if a revelation be made to another sitting by, let the first keep silence." — 1 Corinthians 14:30 (ASV)

But if anything be revealed to another. Here is another advantage—that whenever there is occasion, the way will also be open to them. Therefore, they no longer have any reason to complain that the Spirit is bound, or that his mouth is shut. For all have the opportunity and liberty to speak when there is an occasion for it, provided only that no one inappropriately intrudes—aiming to please himself rather than to serve some useful purpose.

Now he requires this modesty from everyone: that each person in his place should give way to another who has something better to bring forward. For this alone is the true liberty of the Spirit—not that everyone is allowed to rashly speak out whatever he pleases, but that all, from the highest to the lowest, voluntarily allow themselves to be under control, and that the one Spirit is listened to, through whomever he speaks. As for the certainty of the revelation, we will see soon.