It is narrated from Sayyiduna Utbah bin Abd (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "The martyrs and those who died of the plague will come (on the Day of Resurrection), and those who died of the plague will say: We too are martyrs. It will be said: Look; if their wounds are flowing with blood like the wounds of the martyrs and giving off the fragrance of musk, then they are martyrs. And they will find them to be so."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 14364