Sa'id bin Zaid (RAA) narrated that the Messenger of Allah (ﷺ) said:
"Whoever is killed while protecting his property, he is a martyr." Related by the four Imams and At-Tirmidhi graded it as Sahih. (ID)
English reference (ID): Book 10, Hadith 1295 (ID)
Arabic reference (ID): Book 10, Hadith 1256 (ID)