Narrated Abu Huraira (radiallaahu `anhu):
Allah's Apostle (sallallaahu `alayhi wasallam) said, "Verily, Belief returns and goes back to Medina as a snake returns and goes back to its hole (when in danger)."
So just like a snake returns to its hole when in danger, similarly Islam will return to Madinah in its true form when it'll be in danger (due to trials, doubts etc.), since Madinah was where it came out (emerged) from.
Whoever then wishes to save their Imaan can go to Madinah, for Imaan only grows while living there; so does the love for Prophet (sallallaahu `alayhi wasallam). <3