Isaiah prophesied to the kings and people of Judah in the late 8th century BC, when Judah faced the threat of the Assyrian Empire. He emphasized that Judah should turn to God and trust in him for protection from the Assyrians rather than relying on political alliances with Egypt or Babylon.
The prophecies in Isaiah 21-22 are part of that overall message. In Isaiah 21:1-10, Isaiah looks ahead to the fall of Babylon, which came almost two centuries after Isaiah in 539 BC. In verse 2, he sees allies Elam and Media turning against Babylon.
In verses 3-4, Isaiah speaks of the anguish he experiences because of what is coming in the future. Perhaps he laments for those in Judah who are putting their trust in Babylon. He may see the grief of those who will be taken into captivity in Babylon in 606-586 BC
Commentator John Oswalt notes that verse 5 reminds us of the scene in Daniel 5, when Babylonian royalty feasts while attackers wait outside their gates. They make frantic preparations for war, "oiling their shields," but it is too late. The handwriting is on the wall.
In verses 6-9 we see the prophet as watchman, warning Judah of the consequences of continuing to disobey God. The horsemen he sees may be part of Babylon's defeated army fleeing. If the Babylonians ultimately will not be able to save themselves in the 6th century, how can they be of help to Judah in the 8th century?
Isaiah's next oracle in 21:11-12 comes to Dumah. There are a couple of different possibilities for the identity of Dumah. The LXX has "Idumea" (Edom) here, Seir in verse 11 is another name for Edom, and "Dumah" is an anagram of "Edom." So this could be a message for Edom.
On the other hand, Dumah is the name of an Arabian oasis at the intersection of two trade routes, so the oracle may be directed to this location. Certainly Edom and Arabia both would be interested in what to expect from the Assyrians and Babylonians. They might even ask Judah's watchman what he sees.
The watchman's words are cryptic: "Morning comes, and also the night." Oswalt proposes that Isaiah may be saying that the Assyrian "night" will end, but it will be replaced by a Babylonian "night." Or perhaps he is saying that Sennacherib will be defeated when he tried to take Jerusalem in 701 BC, but then Assyria would go on to defeat Babylon in 689 BC.
There is an oracle to Arabia in 21:13-17. Oswalt explains that Tema is another oasis about 200 miles south of Dumah on the road to the Red Sea, while Dedan is about 90 miles south of Tema. All of these sites are part of Kedar (v 16). The fugitives in verse 14 may be fleeing Babylon or heading south from Dumah. In any case, Kedar will not be safe by allying itself with Babylon. It will fall along with Babylon.
In chapter 22 Isaiah has a message for Jerusalem. Oswalt proposes that the setting may be a time when Judah is temporarily rejoicing after being spared from an Assyrian attack. One possibility is 711 BC, when the Assyrians took the Philistine city of Azekah but then withdrew. Judah moved to shore up Israel's defenses (verses 8-11), but its best defense would be to turn to God in repentance (verse 12). They would not be forgiven if they did not humble themselves (verse 14).
Isaiah illustrates right and wrong approaches in the rest of chapter 22. Shebna, a high official who should have been working to serve the nation, is preoccupied with his own legacy by supervising the construction of a tomb (verses 15-19). Shebna would be removed from office and replaced by Eliakim (verse 20), who would serve faithfully (verses 21-23). Sadly, Eliakim would not be stand up under the strain of burdens placed upon him by his family (verses 24-25). Still, he had the right priorities.
Oswalt observes that these prophecies in Isa 21-22 teach us about
- the sovereignty of God.
- the folly of trusting human power.
- the fickleness of human promises.