Sahih Bukhari Volume 2, Book 24, Hadith 1461

حَدَّثَنَا عُمَرُ بْنُ حَفْصِ بْنِ غِيَاثٍ، حَدَّثَنَا أَبِي، حَدَّثَنَا الأَعْمَشُ، عَنِ الْمَعْرُورِ بْنِ سُوَيْدٍ، عَنْ أَبِي ذَرٍّ ـ رضى الله عنه ـ قَالَ انْتَهَيْتُ إِلَى النَّبِيِّ صلى الله عليه وسلم قَالَ ‏"‏ وَالَّذِي نَفْسِي بِيَدِهِ ـ أَوْ وَالَّذِي لاَ إِلَهَ غَيْرُهُ، أَوْ كَمَا حَلَفَ ـ مَا مِنْ رَجُلٍ تَكُونُ لَهُ إِبِلٌ أَوْ بَقَرٌ أَوْ غَنَمٌ لاَ يُؤَدِّي حَقَّهَا إِلاَّ أُتِيَ بِهَا يَوْمَ الْقِيَامَةِ أَعْظَمَ مَا تَكُونُ وَأَسْمَنَهُ، تَطَؤُهُ بِأَخْفَافِهَا، وَتَنْطَحُهُ بِقُرُونِهَا، كُلَّمَا جَازَتْ أُخْرَاهَا رُدَّتْ عَلَيْهِ أُولاَهَا، حَتَّى يُقْضَى بَيْنَ النَّاسِ ‏"‏‏.‏ رَوَاهُ بُكَيْرٌ عَنْ أَبِي صَالِحٍ عَنْ أَبِي هُرَيْرَةَ ـ رضى الله عنه ـ عَنِ النَّبِيِّ صلى الله عليه وسلم‏

Narrated By Abu Dhar : Once I went to him (the Prophet) and he said, "By Allah in Whose Hands my life is (or probably said, 'By Allah, except Whom none has the right to be worshipped) whoever had camels or cows or sheep and did not pay their Zakat, those animals will be brought on the Day of Resurrection far bigger and fatter than before and they will tread him under their hooves, and will butt him with their horns, and (those animals will come in circle): When the last does its turn, the first will start again, and this punishment will go on till Allah has finished the judgments amongst the people."