King James Version
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.English Standard Version
Thus tongues are a sign not for believers but for unbelievers, while prophecy is a sign not for unbelievers but for believers.New International Version
Tongues, then, are a sign, not for believers but for unbelievers; prophecy, however, is for believers, not for unbelievers.