Jamieson, Fausset and Brown on Hebrews 10:27

27. a certain--an extraordinary and indescribable. The indefiniteness, as of something peculiar of its kind, makes the description the more terrible (compare Greek, Jas 1:18).

looking for--"expectation": a later sense of the Greek. Alford strangely translates, as the Greek usually means elsewhere, "reception." The transition is easy from "giving a reception to" something or someone, to "looking for." Contrast the "expecting" (the very same Greek as here), He 10:13, which refutes Alford.

fiery indignation--literally, "zeal of fire." Fire is personified: glow or ardor of fire, that is, of Him who is "a consuming fire."

devour--continually.