12 Is my strength the strength of stones? or is my flesh of brass 
12 Do I have the strength of stone? Is my flesh bronze?
12 Is my strength the strength of stones, or is my flesh bronze?
12 Do you think I have nerves of steel? Do you think I'm made of iron?
12 Is my strength the strength of stones? Or is my flesh bronze?
12 Do I have the strength of a stone? Is my body made of bronze?
Matthew Henry's Commentary on Job 6:12
Commentary on Job 6:8-13
(Read Job 6:8-13)
Job had desired death as the happy end of his miseries. For this, Eliphaz had reproved him, but he asks for it again with more vehemence than before. It was very rash to speak thus of God destroying him. Who, for one hour, could endure the wrath of the Almighty, if he let loose his hand against him? Let us rather say with David, O spare me a little. Job grounds his comfort upon the testimony of his conscience, that he had been, in some degree, serviceable to the glory of God. Those who have grace in them, who have the evidence of it, and have it in exercise, have wisdom in them, which will be their help in the worst of times.