Sahih Bukhari Volume 9, Book 87, Hadith Number 161.

Narrated By ‘Abdullah : The Prophet said, “I saw (in a dream) a black woman with unkempt hair going out of Medina and settling at Mahai’a, i.e., Al-Juhfa. I interpreted that as a symbol of epidemic of Medina being transferred to that place (Al-Juhfa).”