Musnad Ahmad 459:24

Abu al-Yaman narrated to us, Isma'il ibn 'Ayyash narrated to us, from Buhayr ibn Sa'd, from Khalid ibn Ma'dan, from Ibn Abi Bilal, from al-'Irbad ibn Sariyah, who said: I heard the Prophet, peace and blessings of Allah be upon him, saying: "The martyrs and those who died on their beds will dispute before Allah, the Almighty and Majestic, regarding those who died of the plague. The martyrs will say: 'Our brothers were killed.' And those who died on their beds will say: 'Our brothers died on their beds just as we died.' Allah, the Almighty and Majestic, will judge between them: 'Look at the wounds of those who died of the plague; if they resemble the wounds of the martyrs, then they are among them.' They will look at the wounds of those who died of the plague, and if they resemble them, they will be joined with them."