C. F. Keil and Franz Delitzsch on Isaiah 5:27

Isa 5:27 “There is none exhausted, and none stumbling among them: it gives itself no slumber, and no sleep; and to none is the girdle of his hips loosed; and to none is the lace of his shoes broken.” Notwithstanding the long march, there is no exhausted one, obliged to separate himself and remain behind (Deu 25:18; Isa 14:31); no stumbling one (Cōshēl), for they march on, pressing incessantly forwards, as if along a well-made road (Jer 31:9). They do not slumber (nūm), to say nothing of sleeping (yâshēn), so great is their eagerness for battle: i.e., they do not slumber to refresh themselves, and do not even allow themselves their ordinary night’s rest. No one has the girdle of his armour-shirt or coat of mail, in which he stuck his sword (Neh 4:18), at all loosened; nor has a single one even the shoe-string, with which his sandals were fastened, broken (nittak, disrumpitur). The statement as to their want of rest forms a climax descendens; the other, as to the tightness and durability of their equipment, a climax ascendens: the two statements follow one another after the nature of a chiasmus.