Sahih Bukhari Volume 7, Book 71, Hadith Number 630.

Narrated By ‘Aisha : (The wife of the Prophet) that she asked Allah’s Apostle about plague, and Allah’s Apostle informed her saying, “Plague was a punishment which Allah used to send on whom He wished, but Allah made it a blessing for the believers. None (among the believers) remains patient in a land in which plague has broken out and considers that nothing will befall him except what Allah has ordained for him, but that Allah will grant him a reward similar to that of a martyr.”