There shall be great rejoicing and praising God, both with vocal and instrumental music, for this glorious and stupendous work of the conversion of the Gentiles. He describes evangelical worship by legal phrases and customs, as the prophets frequently do. In thee, i.e. in Zion, or the church. These words may be here added as the burden or matter of the song, which these singers are supposed to have sung; and that either,
1. In their own names, and in the name of all the Zionites or people of God. So the sense is, All our desires and delights are in thee, all the springs of mercy, grace, and glory flow to us only in and through thee; for springs or fountains are oft put for all precious or desirable things, as Psalms 36:9 Isaiah 12:3 Hosea 13:15. Or,
2. In God's name, whose words were frequently sung by the singers in the Old Testament. And so the sense is, All the springs or fountains of good things, or of my blessings are in Zion, or in the church, out of which no true blessings are to be expected or found. And this sense seems best to suit with the phrase, my springs; partly because it seems more proper to call them God's springs, who is the author and giver of them, than men's springs, who are only the receivers of them; and partly because this is more agreeable to the phrase and usage of Scripture, which every where ascribes and appropriates them to God.