Charles Ellicott Commentary Isaiah 30:5

"They shall all be ashamed because of a people that cannot profit them, that are not a help nor profit, but a shame, and also a reproach." — Isaiah 30:5 (ASV)

They were all ashamed ... —Better, are: historic present, as before. The prophet paints the dreary disappointment of the embassy. They found Egypt at once weak and false, without the will or power to help them. So Rabshakeh compares that power to “a broken reed,” which only pierces the hand of the one who leans on it. So Sargon (Smith, Assyrian Canon, p. 133, quoted by Cheyne), describing the resistance of his foes, says that they “carried presents, seeking his alliance, to Pharaoh, king of Egypt, a monarch who could not help them.”