John Gill's Exposition of the Whole Bible
Isaiah 28:9
Whom shall he teach knowledge?.... Not the drunken priest or prophet, who were both unfit for teaching men knowledge; but either the true and godly priest or prophet of the Lord, or the Lord himself, before spoken of as a spirit of judgment, Isaiah 28:6 namely, by his prophets and ministers, the latter seem rather intended; whom may or can such an one teach the knowledge of God, and of themselves; the knowledge of the law, and of the Gospel; the knowledge of divine truths, of things necessary to salvation, and the conduct of human life; of Jesus Christ, and the way of salvation by him, and of him, as a foundation of the Lord's laying in Zion, hereafter mentioned in this chapter? who are capable of receiving such instructions? it intimates the stupidity and sottishness of the Jews, whose minds were so impaired by excessive drinking, that they were not able to take in the knowledge of these things:
and whom shall he make to understand doctrine? or "hearing"; the hearing of the word, or the word heard, the report of the Gospel; so the word is used in Isaiah 53:1 this will never be understood, believed, and received, unless the arm of the Lord is revealed, or his power be exerted; prophets and ministers may speak to the ears of men, but they cannot give them an understanding of divine things, God only can do that: here it designs, as before, the unteachableness of the people of the Jews, being in the circumstances they were, as appears by what follows:
[them that are] weaned from the milk, [and] drawn from the breasts; signifying, that one might as well take children from the breast, such as are just weaned, and instruct them, as to pretend to teach these people the knowledge of divine things, or cause them to understand sound doctrine, that which is agreeable to law and Gospel; so sottish were they become through excessive drinking. Some understand this as a serious answer to the questions, and of persons in a metaphorical sense, who desire and thirst after the sincere milk of the word, as children just taken from the breast, and deprived of it, do; and who are afflicted and distressed, and without the milk of divine comfort, and are like weaned children, humble, meek, and lowly; see
Matthew 11:25. Jarchi makes mention of such an interpretation as this, "them that are weaned from the milk"; from the law, which is called milk: "and drawn from the breasts"; drawn from the disciples of the wise men. It may be understood of such who departed from the sincere milk of the word; and embraced the traditions of the elders.