Charles Ellicott Commentary Isaiah 56:10

"His watchmen are blind, they are all without knowledge; they are all dumb dogs, they cannot bark; dreaming, lying down, loving to slumber." — Isaiah 56:10 (ASV)

His watchmen are blind. — These are the guides of the people, and especially the self-styled prophets, who are blind to the signs of the times, who are dumb, and give no warning to the people of the real dangers that threaten them, who prophesy for the rewards of divination (Numbers 22:7; 1 Samuel 9:7; Nehemiah 6:12), and who are conspicuous for their luxury and intemperance.

Given the men described in Isaiah 5:22, Isaiah 28:7–8, and Isaiah 30:10, and the circumstances of Manasseh’s reign, no other result could be expected.

Sleeping. — The prophet, with a scornful irony, substitutes hozîm (“dreamers”) for khozîm (“seers”). The lying down contrasts their indolent and easy life with the vigil and the fast of a true prophet.