Charles Ellicott Commentary Isaiah 21:5

"They prepare the table, they set the watch, they eat, they drink: rise up, ye princes, anoint the shield." — Isaiah 21:5 (ASV)

Prepare the table, watch in the watchtower.—These words (a historical infinitive) are better understood as indicative: They prepare ... they watch. The last clause has been rendered in various ways: they spread the coverlet; that is, for the couches of the revelers (Amos 6:4); and they take horoscopes (Ewald).

Here, with hardly a shadow of a doubt, there is a reference to the spirit of reckless revelry that immediately preceded the capture of Babylon. The prophet perhaps had something analogous to such blind security before his eyes at the very time he was writing (Isaiah 22:13), which led him to anticipate a similar state of affairs in Babylon.

Anoint the shield ...—This summons, in the prophet’s vision, breaks in on the songs and music of the revelry. The shields referred to were those covered with leather, which was oiled, partly to protect it from moisture and partly to make a sword's stroke glide off it. The call implies that even this precaution had been neglected by the revelers.