Sahih Bukhari
Divine Will (Al-Qadar)
Volume: 008 / Book Number: 077 / Hadith Number: 616
Narrated 'Aisha:
I asked Allah's Apostle about the plague. He said, "That was a means of torture which Allah used to send upon whom-so-ever He wished, but He made it a source of mercy for the believers, for anyone who is residing in a town in which this disease is present, and remains there and does not leave that town, but has patience and hopes for Allah's reward, and knows that nothing will befall him except what Allah has written for him, then he will get such reward as that of a martyr."