In the law it is written. — The preceding teaching is illustrated and enforced by an appeal to Jewish history. The Old Testament as a whole was not infrequently thus designated “the Law.” (See John 10:34; John 12:34; John 15:25.) The words are scarcely a quotation, but rather an illustration taken from Isaiah 28:9-12. The passage there refers to the refusal of Israel to hearken to Jehovah when He spoke to them with clearness and simplicity, and His judgment on them taking the form of declaring that He would make a foreign people — the Assyrians — be His mouthpiece to them in the future, in a language which they knew not. It is as if the Apostle said: Remember there was a time in Jewish history when an unintelligible language was a sign sent by God, and proved unavailing as regards the conversion of Israel. The gift which you so exalt now is equally useless by itself for that same purpose.
Related Commentaries of 1 Corinthians 14:21
1 Corinthians 14:21-22
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.