Albert Barnes Commentary Isaiah 29:24

"They also that err in spirit shall come to understanding, and they that murmur shall receive instruction." — Isaiah 29:24 (ASV)

They also who erred in spirit — .

Shall learn doctrine — When this would occur the prophet does not state. It may be intended to denote the times of Hezekiah; or the times subsequent to the captivity; or possibly it may refer to the times under the Messiah. All that the prophet teaches is that at some future period in the history of the Jews, there would be such a reform that they would be regarded as the worthy descendants of the pious patriarch Jacob.