Job 2:4

Skin for skin— A proverbial expression, to denote the great value in which life is held; insomuch that a man, to preserve it, would suffer even his skin to be torn off. It may signify also, that a man, in order to save his life, would willingly suffer himself to be stripped of all his fortunes. The words נפשׁו בעד bead napsho, rendered for his life, might be more properly rendered, for his person. The question here was not about his life; Satan had not the impudence to desire his life; but only to smite him in his bone, and in his flesh; and accordingly, the permission given him in the 6th verse implies this restriction, beware thou touch not his life. The rendering the word נפשׁ nepesh, by person, is not unusual, as may be seen by any one who will consult the Concordances. See Heath and Schultens.