It is essential to feed the slave, clothe him (properly) and not burden him with work which is beyond his power. (Using translation from Muslim 1662)
أَنَّ رَسُولَ اللهِ ﷺ قَالَ لِلْمَمْلُوكِ طَعَامُهُ وَكِسْوَتُهُ بِالْمَعْرُوفِ وَلَا يُكَلَّفُ مِنَ الْعَمَلِ إِلَّا مَا يُطِيقُ