'Harps' in the Bible

And I heard a voice from heaven, like the sound of great waters and like the rumbling of mighty thunder; and the voice that I heard [seemed like music and] was like the sound of harpists playing on their harps.

Then I saw something like a sea or large expanse of glass mixed with fire, and those who were victorious over the beast and over his image and over the number corresponding to his name were standing on the sea or large expanse of glass, holding harps of God [worshiping Him].