Sahih Bukhari Volume 004, Book 056, Hadith Number 679.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 56. Virtues and Merits of the Prophets (PBUH) and his Companions
Narated By Usama bin Zaid : Allah's Apostle said, "Plague was a means of torture sent on a group of Israelis (or on some people before you). So if you hear of its spread in a land, don't approach it, and if a plague should appear in a land where you are present, then don't leave that land in order to run away from it (i.e. plague)."