Sayyiduna al-Irbad bin Sariyah (may Allah be pleased with him) said: I heard the Messenger of Allah (peace and blessings be upon him) say: "The martyrs and those who died (a natural death) on their beds will dispute before our Lord concerning those who died in the plague. The martyrs will say: 'These are our brothers; they were killed (by the plague) just as we were killed.' And those who died on their beds will say: 'These are our brothers; they died just as we died on our beds.' Then Allah Almighty will judge between them and will say: 'Look at the wounds of those who died of the plague; if they resemble the wounds of the martyrs, then they are among the martyrs and with them.' So they will look at the wounds of those who died of the plague, and they will resemble the wounds of the martyrs, and so they will be joined with them."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 15717