Charles H. Spurgeon on Psalms 55:19

They have no changes, etc. Who are they who have no changes? Apparently those whom God is said to humble or chastise. And what is the meaning of the word, changes as here used? Many understand it of a moral change; "who are without change of heart or reformation." But the word never occurs in this sense. It means, properly, "a change" in the sense of succession; as of garments, of troops relieving guard, servants leaving work, and the like. Hence it would rather mean in a moral sense: "They who have no cessation in their course (by being relieved guard, for instance), who always continue, and persevere in their evil life." Calvin and others understand it of change of fortune, i.e., "who are always prosperous; "but this again is not supported by usage. J. J. Stewart Perowne.