The real slave, protects, many more, the family "soul" ... sent by AllahCC .. not only the blood.
those who utter words offensive to a stranger, are against the command from Allah CC
Those who utter words offensive to a family member .... are in accordance with the malice of Devil (may protect us from it Alllah cc) to "destroy" a creature.
(The worst torture is psychological)
hz Ali (ra)