(Background – from ESV Study Bible) The story of Job has its setting outside Israel to the east and south (Uz is related to Edom, which may be the setting of the book), the author of Job is a Hebrew, thoroughly immersed in the Hebrew Scriptures. The time in which the account of Job is set is not known with precision – many consider the context of Job’s culture and put him in the time of Abraham.
The earliest reference to Job outside the book itself is in Ezekiel. The prophet names three paragons of virtue (chap 14:12 – 14): And the word of the LORD came to me: "Son of man, when a land sins against me by acting faithlessly, and I stretch out my hand against it and break its supply of bread and send famine upon it, and cut off from it man and beast, even if these three men, Noah, Daniel, and Job, were in it, they would deliver but their own lives by their righteousness, declares the Lord GOD.” It is not certain whether Ezekiel knew of these men from the biblical narrative or if his knowledge was from God. If Ezekiel knew of Job through the biblical book, then Job would have lived prior to the Babylonian exile.
The author of Job makes direct allusion to the Hebrew Scriptures (e.g., Ps. 8:4; cf. Job 7:17–18), and at times quotes lines directly (Ps. 107:40; Isa. 41:20; cf. Job 12:21, 24). Such precise repetition of phrases and reapplication of biblical thought indicates that Job had access to these writings, though again it cannot be certain in what form they existed. The author uses a lot of vocabulary with meanings known in later Hebrew. This does not confirm a more precise dating but may favor a date that is during or after the Babylonian exile (538 BC). It would appear that this book may have been written as many as 600 years after Job lived – not without precedent in Scripture, as Moses wrote Genesis some 2,700 years after Creation. None of this is cause for worry, as it is God Who is the primary author of all Scripture.
The book of Job asks the question – “Can God be trusted?” It is fair to say that most of our attention is on Job and his loss and the rough treatment received at the hands of his friends and wife. But the lesson we are to gain from this book is found in the reply from God; that He alone can be trusted, that He alone is creator and sovereign – He is God and He is not obligated to answer His creatures! This maddens those who deny His existence or sovereignty, but ought to comfort us who are redeemed by Christ. If God is not sovereign over all things, He cannot be trusted in anything.