John Bunyan's 'The Pilgrim’s Progress' (published 1678) makes reference to "crossing the River" in order to get to the Celestial City. Chapter 20 mentions that only Enoch and Elijah did not have to cross the River. FAITH is needed to make the crossing from this life to the next.
In Chapter 34 Christiana crosses the River, along with many other pilgrims. All have been summoned to make the crossing.
My question is about the origins of the expression "crossing over Jordan" and whether this is commonly understood as an allegory of the believer passing over from this life to the next, or if it could mean something else.
I'm looking for source material/references to help me trace this expression and understand how various Christian traditions understand it. Is “crossing over Jordan” a metaphor or a figure of speech for the believer passing from physical death to heaven?