Musnad Abu Ya'la al-Mawsili 160:178

Abu Hisham al-Rifa'i narrated to us, Ibn Fudayl narrated to us, 'Abdullah bin Sa'id bin Abi Sa'id narrated to us, from his grandfather, from Abu Hurayrah, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "If the son of Adam had two valleys of gold, he would seek a third. And nothing fills the belly of the son of Adam except dust."