The Messenger of Allah ﷺ said: If anyone asks Allah for martyrdom sincerely, Allah will make him reach the ranks of martyrs even if he died on his bed. (Using translation from Abū Dāʾūd 1520)  

أَنَّ رَسُولَ اللهِ ﷺ قَالَ «مَنْ سَأَلَ اللهَ الشَّهَادَةَ بِصِدْقٍ بَلَّغَهُ اللهُ مَنَازِلَ الشُّهَدَاءِ وَإِنْ مَاتَ عَلَى فِرَاشِهِ»  

"There are five things, whoever dies of any of them is a martyr. The one who is killed in the cause of Allah is a martyr; the one who dies of an abdominal complaint in the cause of Allah is a martyr; the one who dies of the plague in the cause of Allah is a martyr; and the woman who dies in childbirth in the cause of Allah is a martyr." (Using translation from Nasāʾī 3163)  

أَنَّ رَسُولَ اللهِ ﷺ قَالَ خَمْسٌ مَنْ قُبِضَ فِي شَيْءٍ مِنْهُنَّ فَهُوَ شَهِيدٌ الْمَقْتُولُ فِي سَبِيلِ اللهِ شَهِيدٌ وَالْغَرِيقُ فِي سَبِيلِ اللهِ شَهِيدٌ وَالْمَبْطُونُ فِي سَبِيلِ اللهِ شَهِيدٌ وَالْمَطْعُونُ فِي سَبِيلِ اللهِ شَهِيدٌ وَالنُّفَسَاءُ فِي سَبِيلِ اللهِ شَهِيدٌ  

"The martyrs and those who dies in their beds referred a dispute to our Lord concerning those who dies of the plague. The martyrs said: 'Our brothers were killed as we were killed.' And those who dies in their beds said: 'Our brothers dies on their beds as we died.' Our Lord said: 'Look at their wounds; if their wounds; if their wounds are like the wounds of those who were killed then they are of them and belong with them.' And their wounds were like their (the martyrs') wounds." (Using translation from Nasāʾī 3164)  

أَنَّ رَسُولَ اللهِ ﷺ قَالَ يَخْتَصِمُ الشُّهَدَاءُ وَالْمُتَوَفَّوْنَ عَلَى فُرُشِهِمْ إِلَى رَبِّنَا فِي الَّذِينَ يُتَوَفَّوْنَ مِنَ الطَّاعُونِ فَيَقُولُ الشُّهَدَاءُ إِخْوَانُنَا قُتِلُوا كَمَا قُتِلْنَا وَيَقُولُ الْمُتَوَفَّوْنَ عَلَى فُرُشِهِمْ إِخْوَانُنَا مَاتُوا عَلَى فُرُشِهِمْ كَمَا مُتْنَا فَيَقُولُ رَبُّنَا انْظُرُوا إِلَى جِرَاحِهِمْ فَإِنْ أَشْبَهَ جِرَاحُهُمْ جِرَاحَ الْمَقْتُولِينَ فَإِنَّهُمْ مِنْهُمْ وَمَعَهُمْ فَإِذَا جِرَاحُهُمْ قَدْ أَشْبَهْتَ جِرَاحَهُمْ