Charles Ellicott Commentary Job 18:13

"The members of his body shall be devoured, [Yea], the first-born of death shall devour his members." — Job 18:13 (ASV)

The strength of his skin. — This verse should probably be rendered, It shall devour the members of his body, even the firstborn of death shall devour his members; and by the “firstborn of death” is probably to be understood some wasting disease such as Job’s, the phrase being so used as a euphemism.