Because of his glimmer of hope and because he has faith in the God of the promise (however, weak that faith may be), Job knows his friends cannot help him. This is why his hope is in God. As Job’s mood swings widely, even to the point of despair as seen in Job 17:16-17, nevertheless, Job mocks his friends in the balance of Job 17.
“You have closed their minds to understanding; therefore you will not let them triumph. . . . `God has made me a byword to everyone, a man in whose face people spit. My eyes have grown dim with grief; my whole frame is but a shadow. Upright men are appalled at this; the innocent are aroused against the ungodly. Nevertheless, the righteous will hold to their ways, and those with clean hands will grow stronger. `But come on, all of you, try again! I will not find a wise man among you. My days have passed, my plans are shattered, and so are the desires of my heart. . . . If the only home I hope for is the grave, if I spread out my bed in darkness, if I say to corruption, `You are my father,’ and to the worm, `My mother’ or ‘My sister,’ where then is my hope? Who can see any hope for me? Will it go down to the gates of death? Will we descend together into the dust?’”
Not only is Job now giving as good as he is getting, only a man with faith and hope will fight back–as Job is now doing.