Sahih al-Bukhari 3474
صحيح البخاري#3474SahihNarrated `Aisha:(the wife of the Prophet) I asked Allah's Messenger (ﷺ) about the plague. He told me that it was a Punishment sent by Allah on whom He wished, and Allah made it a source of mercy for the believers, for if one in the time of an epidemic plague stays in his country patiently hoping for Allah's Reward and believing that nothing will befall him except what Allah has written for him, he will get the reward of a martyr
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 60:141