Language:
كتاب الحدود
86  
Limits and Punishments set by Allah (Hudood)
(45)
Chapter: Slandering the slaves
(45)
باب قَذْفِ الْعَبِيدِ
Sahih al-Bukhari 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 ‏"‏‏.‏
Reference : Sahih al-Bukhari 6858
In-book reference : Book 86, Hadith 80
USC-MSA web (English) reference : Vol. 8, Book 82, Hadith 841
  (deprecated numbering scheme)