Matthew Poole and continuators on Isaiah 21:5

5 Prepare the table , watch in the watch-tower , eat, drink: arise, ye Princes , and anoint the shield .

Furnish it with Meats and Drinks, as it follows. The Prophet foretells what the Babylonians would be doing when their Enimies were at their Doors, that they would give up themselves to Feasting and Security.

To give us notice of any approaching danger, that in the mean time we may more securely indulge our selves in Mirth and Pleasures.

Either, 1. ye Medes and Persians: Whilst your Enemies the Babylonian's are feasting securely, prepare to make your Assault. Or, 2. ye Princes of Babylon: Arise from the Table and run to your Arms. Which sudden alarm and change of their Posture proceeded from Tidings out of the Watch-tower, as may be gathered from the former Clause, and is more fully expressed in the following Verses.

Prepare your selves and your Arms for the Battel approaching. The shield is put for all their weapons of Offence and Defence. They used to Anoint their Shields with Oyl, partly to preserve and polish them; and partly to make them slippery, that their Enemies Darts might not fasten in them, but slide off from them.