Sunan an-Nasa'i, Volume 3, Book 23, Hadith 2474 (DarusSalam) ⓘ
It was narrated from Abu Hurairah that the Prophet said: "The Muslim does not have to pay Sadaqah on his slave or his horse."
أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا حَمَّادٌ، عَنْ خُثَيْمِ بْنِ عِرَاكِ بْنِ مَالِكٍ، عَنْ أَبِيهِ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ النَّبِيَّ صلى الله عليه وسلم قَالَ " لَيْسَ عَلَى الْمُسْلِمِ صَدَقَةٌ فِي غُلاَمِهِ وَلاَ فِي فَرَسِهِ " .
also referenced under: Hadith 2472 (Reference) & Book 23, Hadith 0 (In-Book)