Nafi’ reported: Ibn Umar, may Allah be pleased with him, said, “Every piece of property on which alms is paid, even if it were beneath the seven earths, it will never be buried. Every piece of property on which alms is not paid is buried, even if it were to lie openly on the face of the earth.”
Source: al-Sunan al-Kubrá lil-Bayhaqī 7230
Grade: Sahih (authentic) according to Al-Bayhaqi
عَنْ نَافِعٍ عَنِ ابْنِ عُمَرَ رضي الله عنه قَالَ كُلُّ مَالٍ أَدَّيْتَ زَكَاتَهُ وَإِنْ كَانَ تَحْتَ سَبْعِ أَرَضِينَ فَلَيْسَ بِكَنْزٍ وَكُلُّ مَالٍ لَا تُؤَدِّي زَكَاتَهُ فَهُوَ كَنْزٌ وَإِنْ كَانَ ظَاهِرًا عَلَى وَجْهِ الْأَرْضِ
7230 السنن الكبرى للبيهقي
4/82 المحدث البيهقي خلاصة حكم المحدث صحيح موقوفاً في السنن الكبرى للبيهقي