21:1ff The short message in 20:45-48 introduces the first of three messages about the judgments that would come upon Jerusalem: (1) the sword of the Lord (21:1-7); (2) the sharpened sword (21:8-17); (3) the sword of Nebuchadnezzar (21:18-22). The city would be destroyed because it was defiled. According to Jewish law, defiled objects were to be passed through fire in order to purify them (see Numbers 31:22, 23; Psalm 66:10-12; Proverbs 17:3). God’s judgment is designed to purify; destruction is often a necessary part of that process.
21:12 Pounding the thighs was a gesture of grief.
21:18-23 Ammon evidently rebelled against Babylon about the same time as King Zedekiah of Judah. In 589 B.C. the nations of Judah and Ammon were among those who conspired against Babylon (Jeremiah 27:3). Ezekiel gave this message to the exiles who had heard the news and were again filled with hope of returning to their homeland. Ezekiel said that Babylon’s king would march his armies into the region to stop the rebellion. Traveling from the north, he would stop at a fork in the road, one way leading to Rabbah, the capital of Ammon, and the other leading to Jerusalem, the capital of Judah. He had to decide which city to destroy. Just as Ezekiel predicted, King Nebuchadnezzar went to Jerusalem and besieged it.
21:21 Nebuchadnezzar had two ways to get advice on the future. One was shaking arrows, much like drawing straws, to see which course of action was right; the second was having priests inspect the liver of a sacrificed animal to see if its shape and size would indicate a decision.
21:27 Instead of using exclamation points for emphasis, the Hebrew language uses repetition. The repetition of overturn shows the certainty of the end of the old order—the world as it is now. The new order—the world as God intends it—will come when he “whose right it is” (the Messiah) returns and sets up his righteous Kingdom.
21:28 The Ammonites and Israelites were usually fighting with each other. God told the Israelites not to ally with foreign nations, but Judah and Ammon united against Babylon in 589 B.C. (Jeremiah 27:3). God first judged Judah when Nebuchadnezzar first went to Jerusalem (21:22); but Ammon would also be judged, not for allying with Judah, but for watching Jerusalem’s destruction with insulting delight.