“Wherefore tongues are for a sign, not to them that believe, but to them that believe not: but prophesying serveth not for them that believe not, but for them which believe.”
King James Version (KJV)
14:22 Tongues are intended for a sign to unbelievers - To engage their attention, and convince them the message is of God. Whereas prophecy is not so much for unbelievers, as for the confirmation of them that already believe.
1Co 14:22 Wherefore tongues are for a sign . . . to them that believe not. They are a sign to unbelievers, who are moved when they hear the gospel spoken in their tongue by men who have never learned it and do not understand it.