What is the essential argument in favor of the tripartite nature of man?

A common belief regarding the nature of mankind is that we have a body, a soul and a spirit. This is known as the Tripartite Nature of Man. What is the essential argument in favor of this view? I would also be interested to know how early in the Scriptures this is indicated or understood. It would be really interesting to know how the Old Testament speaks of this and whether or not that idea was held by Jewish people prior to the coming of Jesus.