al-Ma'rur bin Suwayd al-Asadi المعرور بن سويد الأسدي أبو أمية الكوفي · The Book of Oaths

We went to Abu Dharr (Ghifari) in Rabadha and he had a mantle over him, and his slave had one like it. We said: Abu Dharr, had you joined them together, it would have been a complete garment. Thereupon he said: There was an altercation between me and one of the persons among my brothers. His mother was a non-Arab. I reproached him for his mother. He complained against me to Allah's Apostle (ﷺ). As I met Allah's Apostle (ﷺ)…

I saw Abu Dharr wearing clothes, and his slave wearing similar ones. I asked him about it, and he narrated that he had abused a person during the lifetime of Allah's Messenger (may peace be upoe. him) and he reproached him for his mother. That person came to Allah's Apostle (ﷺ) and made mention of that to him. Thereupon Allah's Apostle (ﷺ) said: You are a person who has (remnants of) Ignorance in him. Your slaves are brothers of yours.…