Musnad Abu Ya'la al-Mawsili 41:2

Abu Khaythama narrated to us, Sufyan narrated to us, from al-Zuhri, from Talha ibn Abd Allah ibn Awf, from Sa’id ibn Zayd, attributing it to the Prophet (may Allah bless him and grant him peace), who said: "Whoever is killed defending his wealth is a martyr. And whoever wrongfully takes any part of the land, it will be tied around his neck from seven earths."