The Rights of Slaves
One day, Isa (alayhi salaam) came to the cemetery. Turning to one of the dead, Allah revived him, Isa asked:
- Who are you?
- In worldly life I was a porter, making my living carrying luggage of people. Once I transferred the wood belonged to one man, took from them a little chip, I brushed teeth with it. And since the day I died, I am required this chip (since the day of my death, because of the chips I am exposed to the report.
The rights of slaves belong to the category of the most difficult to forgive sins before Allah.
Up to this time, for any reason, we have touched someone's rights, we should immediately ask them for forgiveness. So the Messanger of Allah (peace be upon him) said:
"If anyone infringed the rights of his brother Muslim, let him ask forgiveness before the day comes when there is no dirhams and dinars. If he goes to another world, not compensating the disadvantaged rights, in the judgment of his righteous deeds will be transferred to that person, whose rights he infringed, if pious deeds he will not, then the sins of his brother Muslim will be assigned to him" .
 - Bukhari, Kyyama, 6534; Tirmidhi, Kyyama, 2419.