Sing to the Lord a new song,
    his praise from the ends of the earth,
you who go down to the sea, and all that is in it,
    you islands, and all who live in them.
11 Let the wilderness and its towns raise their voices;
    let the settlements where Kedar lives rejoice.
Let the people of Sela sing for joy;
    let them shout from the mountaintops.
12 Let them give glory to the Lord
    and proclaim his praise in the islands.

‘The Gentile nations shall share equally with the Jews in New-Testament blessings, and therefore shall join in New-Testament praises and acts of worship. There shall be churches set up in Gentile nations and they shall sing a new song.’ Matthew Henry.

It is surely impossible to miss the world-wide vision and reach of these verses. The new thing God is going to do will result in the singing of a new song. It concerns the coming of Gentiles into the church, on an equal footing with the Jews, and sharing in all the blessings of the Kingdom. Of course see this most clearly now, with our New Testament perspective.

”Surely you have heard about the administration of God’s grace that was given to me for you, 3 that is, the mystery made known to me by revelation, as I have already written briefly. 4 In reading this, then, you will be able to understand my insight into the mystery of Christ, 5 which was not made known to people in other generations as it has now been revealed by the Spirit to God’s holy apostles and prophets. 6 This mystery is that through the gospel the Gentiles are heirs together with Israel, members together of one body, and sharers together in the promise in Christ Jesus.” (Ephesians 3:2-6; see also Ephesians 2:11-22).

‘Perhaps the neighbouring countries shared in the joy of the Israelites when they returned out of Babylon and some of them came and joined with them in their praises; but we find not that it was to any such degree as might fully answer this illustrious prophecy, and must conclude that it reaches further, and was fulfilled in that which many other prophecies of the joy of the nations are said in the New-Testament to be fulfilled in, the conversion of the Gentiles to the faith of Christ. When they are brought into the church they are brought to give glory to the Lord; then they are to him for a name and a praise, and they make it their business to praise him. He is glorified in them and by them.’ Matthew Henry.