Musnad Ahmad 1577

It was narrated that Sa’d bin Malik, Khuzaimah bin Thabit and Usamah bin Zaid said: The Messenger of Allah (ﷺ) said: “This plague is a punishment or the remainder of a punishment with which people who came before you were punished. If it occurs in a land where you are, do not leave it, fleeing from it. And if you hear that it is in some land, do not enter it."