Musnad Ahmad 788:222

Bakr ibn Isa narrated to us, he said: Abu Awanah narrated to us, from Abu Balj, he said: Abu Bakr ibn Abi Musa al-Ash'ari narrated it to us, from his father, Abdullah ibn Qais, that the Prophet, peace and blessings of Allah be upon him, mentioned the plague and said: "It is a prick from your enemies among the jinn, and it is martyrdom for the Muslim."