Musnad Abu Ya'la al-Mawsili 243:6

Jubarah narrated to us, Abu Bakr narrated to us, from Ziyad ibn 'Alaqah, from Usamah ibn Sharik, from Abu Musa al-Ash'ari, who said: The Messenger of Allah (ﷺ) said: "O Allah, make the destruction of my Ummah by the spear-thrust (al-ta'n) and the plague (al-ta'un)." They said: "O Messenger of Allah, we have known the spear-thrust, but what is the plague?" He said: "The pricking of your enemies from among the jinn, and in it is martyrdom."