REV 15:2

2 I saw what looked like an ocean [that was made of] glass and mixed with fire. And I saw the people who overcame the beast [by not worshipping it] or its image, or [allowing its agent to mark them with] the number that corresponds to the beast’s name [PRS]. They were standing by the ocean [that looked like it was made] of glass. They had harps [for praising] God.