John Calvin 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)

Then shall the erring in spirit learn wisdom. He again repeats that promise which he previously addressed briefly; for as long as human understanding is struck with ignorance and blindness, even if people enjoy an abundance of every kind of blessing, they are still always surrounded and besieged by ruin. In preparing for the restoration of the Church, the Lord therefore enlightens His own people by His word and illuminates them with the light of understanding—those who previously wandered astray in darkness. He does this by the secret influence of the Spirit, for it would be of little value to be taught by the external word if He did not also instruct our hearts inwardly.

And the murmurers shall learn doctrine. Some commentators translate רוגנים (rōgĕnīm) as “whisperers,” and others as “wanderers.” But it means that those who previously murmured against the prophets and could not endure their warnings will become obedient and submissive; and therefore I have chosen to render it murmurers. Therefore, we see how wonderful God’s mercy is, who brings back to the path those who were highly unworthy and makes them partakers of such great blessings. Let us carefully ponder this subject in private. Is there any one of us who has not sometimes “murmured” against God and despised pure doctrine? Indeed, if God had not softened the obstinate and gently brought them to obey, nearly the whole human race would have perished in its madness.