What does Isaiah 16:5 mean?
Most commentators hold Isaiah to be a genuine prophet and that his oracles are from the Lord. As such, they understand this verse to be a reference to the promised future king of Israel, the Messiah. The surprising thing is that it appears to be spoken by a leader of Moab. The Moabite people mostly worshiped a false god, Chemosh (1 Kings 11:33), and not the Lord of the Israelites.This reference to the future king and glory of Israel comes at the end of an official request. Moab is begging Judah that they be allowed to settle refugees in Judah's territory (Isaiah 16:3–4). This plea for sanctuary is requested until the oppressor who has destroyed their land is finally defeated. When this defeat happens, this Moabite leader continues, the throne in Israel will be "established in steadfast love."
The prophetic message fits perfectly with Isaiah's prophecies in chapter 9 and chapter 11. In fact, Isaiah has written in chapter 2 that the Gentile nations of the world will come willingly to Jerusalem to learn the ways of the Messiah (Isaiah 2:1–4). This text from Moab shows that they are ready for that moment. The contrast between that future king of Israel, the Messiah, and the current superpower, the Assyrians, could not be more stark. The Assyrians are the oppressor which destroys and tramples all underfoot. The Messiah will bring justice, do what is right by all people, and sit on a throne established in love. It is not surprising that would sound good to the leader of a group of Moabite refugees.