Isaiah’s references to the Sabbath occur at the beginning (1:13) and end (56:2, 4, 6; 58:13; 66:23) of his prophecy. The book is framed by an initial condemnation of the Sabbath and a promise that all men will bow to Yahweh from Sabbath to Sabbath.
Along the way, the word is used eight times. Yahweh will turn Israel’s corrupted Sabbaths into delightful Sabbaths, and more: He will break out of the Sabbatical pattern altogether and bring in an eighth day that is also a first.