By the rivers of Babylon,
there we sat down, yea, we wept,
when we remembered Zion.
We hanged our harps upon the willows in the midst thereof.
For there they that carried us away captive required of us a song;
and they that wasted us required of us mirth,
saying,
Sing us one of the songs of Zion.
How shall we sing the LORD'S song in a strange land?
Psalm 137:1-4
So when are those "Harps" taken down from the willows, figuratively speaking, & their melodies unleashed?
And I saw as it were a sea of glass mingled with fire:
and them that had gotten the victory over the beast,
and over his image,
and over his mark,
and over the number of his name,
stand on the sea of glass,
having the harps of God.
And they sing the song of Moses the servant of God,
and the song of the Lamb,
saying,
Great and marvellous are thy works,
Lord God Almighty;
just and true are thy ways,
thou King of saints.
Revelation 15:2,3