Job 3:18 - Matthew Poole's English Annotations on the Holy Bible

The prisoners rest together, i.e. one as well as another; they who were kept in the strongest chains and closest prisons, and condemned to the most hard and miserable slavery, rest as well as those who were captives in much better circumstances. Or, in like manner, (as this word oft signifies,) as those oppressors and oppressed do. The oppressor, or, exacter, or taskmaster, who urgeth and forceth them by cruel threatenings and stripes to greater diligence in the works to which they are condemned. See Exodus 3:7, Exodus 5:6,10,13. Job meddles not here with their eternal state after death, or the sentence and judgment of God against wicked men, of which he speaks hereafter; but only speaks of their freedom from worldly troubles, which is the only matter of his complaint and present discourse.