Charles Ellicott Commentary Isaiah 57:8

"And behind the doors and the posts hast thou set up thy memorial: for thou hast uncovered [thyself] to another than me, and art gone up; thou hast enlarged thy bed, and made thee a covenant with them: thou lovedst their bed where thou sawest it." — Isaiah 57:8 (ASV)

Hast thou set up thy remembrance ... —The noun has been commonly referred to the Mesusah, or memorial text, “Jehovah is our God; Jehovah is one,” which was to be written on the door-posts of each house (Deuteronomy 6:9; Deuteronomy 11:20); and the prophet is supposed to point to the fact that this had been written behind the door, as showing that Israel had been ashamed to confess her creed. The explanation seems tenable, but it is possible that “remembrance” may stand for some idolatrous symbol or inscription which had been substituted for the true confession.

Thou hast discovered thyself. —The figure of the unfaithful wife is carried into its details almost with Ezekiel’s boldness.

Made thee a covenant with them ... —The noun, as the italics show, is implied in the verb. The faithless wife forsook the covenant of her youth with her husband, and made a fresh compact with the adulterers.

Where thou sawest it. — And thou sawest the place, the words being used euphemistically for the obscene image of a Chemosh-like idol.