1 Corinthians 14:20-22

Williams(i) 20 Brothers, stop being children in intelligence, but as to evil keep on being babies; and yet as to intelligence be men of maturity. 21 In the law it is written, "By men of foreign languages and by the lips of foreigners I will speak to this people, but even then they will not listen to me, says the Lord." 22 So speaking in ecstasy is meant as a sign, not for believers but for unbelievers, while prophecy is meant, not for unbelievers but for believers.