Hisgalus 15:2

And I saw, as it were, a yam (sea) of glass, having been mingled with eish (fire); and I saw the menatzakhat HaChayyah (overcomers of the Beast, Anti-Moshiach) and of its Atzav (image) and of the mispar (number) of its name; and I saw them having taken their stand on the yam (sea) of glass, holding nevalim (harps) of HASHEM.