Musnad Ahmad 1153:2120

'Abd al-Samad narrated to us, Dawud—meaning Ibn Abi al-Furat—narrated to us, he said: 'Abdullah ibn Buraydah narrated to us, from Yahya ibn Ya'mar, from 'Aishah, that she said: I asked the Messenger of Allah, peace and blessings of Allah be upon him, about the plague. The Messenger of Allah, peace and blessings of Allah be upon him, informed me: "It was a punishment that Allah would send upon whom He willed, then He made it a mercy for the believers. There is no man who is in the midst of a plague, and he remains in his house, patient and anticipating the reward, knowing that nothing will afflict him except what Allah has written for him, but that there will be for him the like of the reward of a martyr."