5 And in mercy shall the throne be established: and he shall sit upon it in truth in the tabernacle of David, judging, and seeking judgment, and hasting righteousness.
According to Aquila, “his throne will be established in mercy,” or according to Theodotion, “the throne will be established with mercy.” Who will establish the throne? Or how is Christ born from the posterity of David? The throne will be established by the Moabites, according to the text; and Christ who is born from the tent (tabernacle) of David will sit upon the throne. By “the tent of David” the prophet means the church of God. David himself is called christ because from his posterity Christ is born according to flesh. Therefore, the tent (tabernacle) of David is the church, and the throne belongs to the head of the church. It refers to the humanity of Christ. Therefore, one should contemplate on the mystery of Christ revealed in the prophecy only in the Holy Spirit; and in such a cautious contemplation curiosity and speculation must be tamed.
“And a throne will be prepared in mercy, and on it will sit in truth, in the tabernacle of David, one who judges and seeks judgment and quickly renders what is just.” The Hebrews interpret this to mean that Hezekiah, a just man, after having expelled the Assyrians, will retain the throne of David and rule Judah, adjudging the people of God to be subject to himself in truth. Others understand that it is about Christ. With the antichrist reduced to dust and with the oppressor who had trampled all the earth removed, Christ the King will come and sit in the tabernacle of David and render to each person according to his works on the day of judgment. Neither is there any doubt that this chapter prophesies of Christ. But we are also able to understand the same thing in the first advent and to demonstrate in the tabernacle of the church that the surging victories of the churches of Moab in all the earth testify to the dominion of Christ.
(Verse 5) And a throne shall be prepared in mercy, and he shall sit upon it in truth, in the tabernacle of David, judging and seeking judgment, and quickly rendering what is just. The Hebrews interpret this place as follows: After the Assyrian is driven away, the just man Ezechias shall reign over Judah, and he shall retain the throne of David, ruling over the people of God in truth. Others understand it as referring to Christ. After the dust and destroyer of the Antichrist are removed, who trampled upon the whole earth, Christ the king shall come, who shall sit in the tabernacle of David, and on the day of judgment he shall render to all according to their works. And there is no doubt that this chapter predicts about Christ. But we can understand the same thing in his first coming, and show in the Church's tabernacle, that in all the land of Moab the trophies of the Churches rising up testify to the kingdom of Christ.
[AD 339] Eusebius of Caesarea on Isaiah 16:5