As the shadow of death, i.e. terrible and hateful, because it both discovers them and hinders their practices. If they are brought to light or discovered, they are overwhelmed with deadly horrors and terrors. Or, as the words are, and may very agreeably to the Hebrew be rendered thus: but (as the Hebrew particle commonly signifies) they know (Heb. he knoweth, every one of them knoweth, i.e. approveth and loveth) the terrors of the shadow of death, i.e. the grossest darkness of the night, which to other men is as terrible as the shadow of death, but to these men is most acceptable: so this clause is fitly opposed to the former; he hates the light, and he likes darkness.
Related Commentaries of Job 24:17
Job 24:17
17 For the morning is to them even as the shadow of death: if one know them, they are in the terrors of the shadow of death.