Brewer's: Jordan Passed
Death over. Jordan is the Styx of Christian mythology, because it was the river which separated the wilderness [of this world] from the promised land.
If I still hold closely to Him, What hath He at last? Sorrow vanquished, labour ended, Jordan passed.
John Mason Neale, D.D. (Stephen the Sabaite.)
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894