Sayyiduna Usamah bin Zayd, Sayyiduna Sa'd bin Malik and Sayyiduna Khuzaymah bin Thabit (may Allah be pleased with them) said that the Messenger of Allah (peace and blessings be upon him) said: "This illness (meaning the plague) is a filth and a remnant of the chastisement with which a people before you were punished. So when it is in a land, do not enter it; and when it is in a land and you are in it, do not go near it."
Hadith Referenceالمعجم الكبير للطبراني / باب الخاء / 3731