Jamieson, Fausset and Brown on Revelation 14:11

11. for ever and ever--Greek, "unto ages of ages."

no rest day nor night--Contrast the very different sense in which the same is said of the four living creatures in heaven, "They rest not day and night, saying, Holy, holy, holy"; yet they do "rest" in another sense; they rest from sin and sorrow, weariness and weakness, trial and temptation (Re 14:13); the lost have no rest from sin and Satan, terror, torment, and remorse.