Sahih Muslim 1914

Yahya ibn Yahya said: I recited to Malik, from Sumayy, from Abu Salih, from Abu Hurayrah, that the Messenger of Allah said: “While a man was walking along a road, he found a thorny branch on the road and moved it aside. Allah appreciated this deed and forgave him.” He also said: “There are five kinds of martyrs: one who dies of plague, one who dies of an abdominal illness, one who drowns, one who is crushed beneath a building, and one who is martyred in the way of Allah, the Mighty and Majestic.”