Charles Ellicott Commentary Isaiah 28:9

"Whom will he teach knowledge? and whom will he make to understand the message? them that are weaned from the milk, and drawn from the breasts?" — Isaiah 28:9 (ASV)

Whom shall he teach knowledge? —The two verses that follow reproduce the language of the drunkards as they talk scornfully of the prophet: “To whom does he come with what he calls his ‘knowledge’ and his ‘doctrine?’ (better, message, as in Isaiah 28:19). Does he think that they are boys just weaned, who are to be taught the first elements of the religion of the infant school?”

Then, in their mockery, they describe his teaching (Isaiah 28:10) with what was to them its wearisome iteration: “Always precept upon precept, line upon line ... ”—petty rebukes and puerile harping upon the same note, semper eandem canens cantilenam. We can scarcely doubt that Isaiah was indignantly reproducing, as St. Paul does in 2 Corinthians 10:10; 2 Corinthians 11:16–17, the very words, almost the drunken accents, in which the priests and false prophets had spoken of him.