20 Brethren, be not children in understanding: howbeit in malice be ye children, but in understanding be men. 21 In the law it is written, With men of other tongues and other lips will I speak unto this people; and yet for all that will they not hear me, saith the Lord. 22 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.
1 Corinthians 14:20-22