1 Corinthians 14:20-22

MNT(i) 20 Brothers, do not become children in understanding; be babes in malice, but in understanding become mature men. 21 In the Law it is written. With men of other tongues, and by the lips of strangers, will I speak to this people, and even then they will not listen to me, says the Lord. 22 So then the gift of tongues is for a sign, not to believers, but to unbelievers; but prophecy is not for unbelievers, but for those who believe.