It was narrated from Abu Hurairah that the Prophet ﷺ said:
“What do you say among yourselves about the martyr?” They said: “The one who is killed in the cause of Allah.” He said: “In that case the martyrs among my nation would be few. Whoever is killed in the cause of Allah is a martyr; whoever dies in the cause of Allah is a martyr; whoever dies of a stomach disease is a martyr; and whoever dies of the plague is a martyr.”

حَدَّثَنَا مُحَمَّدُ بْنُ عَبْدِ الْمَلِكِ بْنِ أَبِي الشَّوَارِبِ، حَدَّثَنَا عَبْدُ الْعَزِيزِ بْنُ الْمُخْتَارِ، حَدَّثَنَا سُهَيْلٌ، عَنْ أَبِيهِ، عَنْ أَبِي هُرَيْرَةَ، عَنِ النَّبِيِّ ﷺ أَنَّهُ قَالَ " مَا تَقُولُونَ فِي الشَّهِيدِ فِيكُمْ " . قَالُوا الْقَتْلُ فِي سَبِيلِ اللَّهِ . قَالَ " إِنَّ شُهَدَاءَ أُمَّتِي إِذًا لَقَلِيلٌ مَنْ قُتِلَ فِي سَبِيلِ اللَّهِ فَهُوَ شَهِيدٌ وَمَنْ مَاتَ فِي سَبِيلِ اللَّهِ فَهُوَ شَهِيدٌ وَالْمَبْطُونُ شَهِيدٌ وَالْمَطْعُونُ شَهِيدٌ " .