Sahih al-Bukhari, Hadith 6858 ⓘ
Narrated Abu Huraira: I heard Abu-l-Qasim (the Prophet) saying, "If somebody slanders his slave and the slave is free from what he says, he will be flogged on the Day of Resurrection unless the slave is really as he has described him."
حَدَّثَنَا مُسَدَّدٌ، حَدَّثَنَا يَحْيَى بْنُ سَعِيدٍ، عَنْ فُضَيْلِ بْنِ غَزْوَانَ، عَنِ ابْنِ أَبِي نُعْمٍ، عَنْ أَبِي هُرَيْرَةَ ـ رضى الله عنه ـ قَالَ سَمِعْتُ أَبَا الْقَاسِمِ، صلى الله عليه وسلم يَقُولُ " مَنْ قَذَفَ مَمْلُوكَهُ وَهْوَ بَرِيءٌ مِمَّا قَالَ، جُلِدَ يَوْمَ الْقِيَامَةِ، إِلاَّ أَنْ يَكُونَ كَمَا قَالَ " .
also referenced under: Book 86, Hadith 81 (In-Book) & Volume 8, Book 82, Hadith 841 (USC-MSA)