The Prophet ﷺ used to urge people to treat their slaves well, saying, "Feed them from what you eat, clothe them from what you wear, and do not torment the creation of Allah."
كان النبي ﷺ يوصي بالمملوكين خيرا، ويقول: أطعموهم مما تأكلون، وألبسوهم من لبوسكم، ولا تعذبوا خلق الله.
No references are available.
Bukhari reported it in Adab al-Mufrad (188, 199) through two paths from Marwan bin Muawiya, from Fadl bin Mubashshir, who said, "I heard Jabir bin Abdullah say," and then he mentioned it.Fadl bin Mubashshir is the Ansari, Abu Bakr al-Madani. Most scholars of knowledge declared him daif, though Ibn Main said in one narration, "There is no harm in him," Bazzar said, "Salih al-hadith," and Ajli said, "There is no harm in him." A narrator like this can have his hadith graded hasan when it has a sahih basis, and this is one such case.