Musnad Ahmad 9:17

Abu al-Yaman narrated to us, Shu'ayb narrated to us, from al-Zuhri, Talhah ibn 'Abd Allah ibn 'Awf narrated to me, that 'Abd al-Rahman ibn 'Amr ibn Sahl informed him, that Sa'id ibn Zayd said: I heard the Prophet, peace and blessings of Allah be upon him, say: "Whoever usurps a span of land unjustly, it will be hung around his neck from the seven earths."