I believe you are refering to the last half of Job 1:21, which says, "The LORD has given, and the LORD has taken away; Blessed be the Name of the LORD."
It is my understanding that the lesson we should learn from Job, is that we are to serve the LORD not matter what. Even in the face of condemnation and loss.
Also, whith God being omniscient, if He takes something away, don't you think that He would have good reason for it? In Isaiah 55:8, we read, "'For My thoughts are not your thoughts, Nor are your ways My ways,' declares the Lord." We do not always know why God does certain things, or allows certain things. But the point is that we need to be steadfast no matter what God sends us, or takes from us.
And the same God who gives, is the same exact God who takes away.