Therefore tongues are for a sign, not to them that believe, but to them that believe not: but prophesying serves not for them that believe not, but for them that believe.
All Commentaries on 1 Corinthians 14:22 Go To 1 Corinthians 14
John Chrysostom
AD 407
Tongues are a sign to unbelievers not for their instruction, as prophecy is for both believers and unbelievers, but to astonish them.