Sahih Muslim
The Book of Zakat (Kitab Al-Zakat)
Book Number: 005 / Hadith Number: 2282
Anas reported Allah's Messenger (may peace be upon him) as saying: If the son of Adam were to possess two valleys of riches. he would long for the third one. And the stomach of the son of Adam is not filled but with dust. And Allah returns to him who repents.