Sahih Muslim 1914
It has been narrated on the authority of Abu Huraira that the, Messenger of Allah (ﷺ) said:
While a man walks along a path, finds a thorny twig lying on the way and puts it aside, Allah would appreciate it and forgive him The Prophet (ﷺ) said: The martyrs are of five kinds: one who dies of plague; one who dies of diarrhoea (or cholera) ; one who is drowned; one who is buried under debris and one who dies fighting in the way of Allah.
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنْ سُمَىٍّ، عَنْ أَبِي صَالِحٍ، عَنْ 
 أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏"‏ بَيْنَمَا رَجُلٌ يَمْشِي بِطَرِيقٍ وَجَدَ
 غُصْنَ شَوْكٍ عَلَى الطَّرِيقِ فَأَخَّرَهُ فَشَكَرَ اللَّهُ لَهُ فَغَفَرَ لَهُ ‏"‏ ‏.‏ وَقَالَ ‏"‏ الشُّهَدَاءُ خَمْسَةٌ الْمَطْعُونُ
 وَالْمَبْطُونُ وَالْغَرِقُ وَصَاحِبُ الْهَدْمِ وَالشَّهِيدُ فِي سَبِيلِ اللَّهِ عَزَّ وَجَلَّ ‏"‏ ‏.‏