In the Book of Job, after Job has went through his first test from Satan there is another gathering in Heaven and, once again, Satan is there (Job 2:1-3). The result of this gathering is that Job will have to endure another test. This is explained in Job 2:4-6. In verse 4, Satan replies to God with the following statement.
Job 2:4 (NIV):
"Skin for skin!" Satan replied." A man will give all he has for his own life.
But stretch out your hand and strike his flesh and bones,
and he will surely curse you to your face."
What is the meaning of "skin for skin"? It would appear that Satan has "sealed the deal" by skin in exchange for skin.
In Job 19:20 the word skin is recorded twice, although in a different context:
I am nothing but skin and bones;
I have escaped by only the skin of my teeth.
Interestingly, the above verse implies that Job has escaped "death" only by the skin of his teeth. This is after Satan was told by God.
The Lord said to Satan, "Very well, then, he is in your hands; but you must spare his life."
Nine verses with reference to "skin" are recorded in the Book of Job (scroll down to view).