Sahih Muslim Book 001, Hadith Number 0260.
Chapter : Concerning the fact that violable is the blood of one who makes an attempt to take possession of the property of another without any legitimate right. If such a man is killed his abode is Fire and he who dies in protecting his property is a martyr.
It is narrated on the authority of Thabit, that when 'Abdullah b. 'Amr and 'Anbasa b. Abi Sufyan were about to fight against each other, Khalid b. 'As rode to 'Abdullah b. 'Amr and persuaded him (not to do so). Upon this Abdullah b. 'Amr said: Are you not aware that the Messenger of Allah (may peace be upon him) had observed: "He who died in protecting his property is a martyr."
This hadith has been narrated by Muhammad b. Hatim, Muhammad b. Bakr, Ahmad b. 'Uthman Naufali, Abu 'Asim, Ibn Juraij.