From Sahih Muslim (Hadith 4944):
It has been narrated on the authority of Hafsa daughter of Sirin who said:Anas b. Malik asked me the cause of death of Yahya b. 'Abu 'Amra. I said: (He died) of plague. He said: The Messenger of Allah (ﷺ) said that death by plague is martyrdom for a Muslim
Reference: Muslim 4944