From Sahih Muslim (Hadith 4940):
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
Reference: Muslim 4940