حَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنْ عَبْدِ اللَّهِ بْنِ دِينَارٍ، أَنَّهُ قَالَ سَمِعْتُ عَبْدَ اللَّهِ بْنَ عُمَرَ، وَهُوَ يُسْأَلُ عَنِ الْكَنْزِ، مَا هُوَ فَقَالَ هُوَ الْمَالُ الَّذِي لاَ تُؤَدَّى مِنْهُ الزَّكَاةُ ‏.‏

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.' " Translation Not Available

Book Ref: Muwatta Imam Malik Book 17 Hadith 600
Web Ref:  Muwatta Imam Malik Book 17 Hadith 21