Yahya related to me from Malik that Abdullah ibn Dinar said, "Iheard Abdullah ibn Umar being asked what kanz was and he said, 'It iswealth on which zakat has not been paid.' " (FR)
USC-MSA web (English) reference: Book 17, Hadith 21 (FR)
Arabic reference (FR): Book 17, Hadith 600 (FR)