Jamieson, Fausset and Brown on Isaiah 3:9

9. show--The Hebrew means, "that which may be known by their countenances" [Gesenius and Weiss]. But Maurer translates, "Their respect for person"; so Syriac and Chaldee. But the parallel word "declare" favors the other view. Kimchi, from the Arabic, translates "their hardness" (Job 19:3, Margin), or impudence of countenance (Jr 3:3). They have lost not only the substance of virtue, but its color.

witness--literally, "corresponds" to them; their look answers to their inner character (Ho 5:5).

declare--(Jude 13). "Foaming out their own shame"; so far from making it a secret, "glorying" in it (Php 3:19).

unto themselves--Compare "in themselves" (Pr 1:31; 8:36; Jr 2:19; Ro 1:27).