Charles Ellicott Commentary Isaiah 29:8

"And it shall be as when a hungry man dreameth, and, behold, he eateth; but he awaketh, and his soul is empty: or as when a thirsty man dreameth, and, behold, he drinketh; but he awaketh, and, behold, he is faint, and his soul hath appetite: so shall the multitude of all the nations be, that fight against mount Zion." — Isaiah 29:8 (ASV)

It shall even be as when an hungry man ... eateth. —The foes of Jerusalem were greedy of their prey, eager to devour; they thought it was already theirs. The rude awakening found them still empty. The lion of Judah was not to be devoured even by the strong bull of Assyria.