Charles Ellicott Commentary 1 Corinthians 14:22

"Wherefore tongues are for a sign, not to them that believe, but to the unbelieving: but prophesying [is for a sign], not to the unbelieving, but to them that believe." — 1 Corinthians 14:22 (ASV)

Wherefore tongues are for a sign, not to them that believe.—This is not an interpretation of the prophecy alluded to in the previous verse, but St. Paul now returns to the gift of "tongues" as existing in the Church, and introduces a thought regarding this gift suggested by the fact mentioned, namely, that in Israel unintelligible tongues, uttered in their hearing, were a sign to unbelieving Jews. Tongues should not be exalted in importance above prophecy—since the function of the latter is truly more significant than that of the former. Tongues were useful to arrest the attention of unbelievers and, if rightly used, to arouse their convictions; but prophecy is in the highest sense useful for believers.