I saw Abu Dharr at Rabadhah wearing a coarse cloak, and his servant was wearing one just like it.The people said, "Abu Dharr, if you had taken the one your servant is wearing and combined it with this one, it would have made a complete suit, and you could have clothed your servant in a different garment."Abu Dharr replied, "I once insulted a man whose mother was a non-Arab, and I taunted him about his mother. He complained about me to the Messenger of Allah ﷺ, who said, 'Abu Dharr, you are a man in whom there is still some of the pre-Islamic ignorance.' He said, 'They are your brothers. Allah has placed them under your authority. Whoever does not get along with you, sell him, but do not torment the creation of Allah.'"
حدثنا عثمان بن أبي شيبة حدثنا جرير عن الأعمش
رأيت أبا ذر بالربذة وعليه برد غليظ وعلى غلامه مثله قال فقال القوم يا أبا ذر لو كنت أخذت الذي على غلامك فجعلته مع هذا فكانت حلة وكسوت غلامك ثوبا غيره قال فقال أبو ذر إني كنت ساببت رجلا وكانت أمه أعجمية فعيرته بأمه فشكاني إلى رسول الله فقال يا أبا ذر إنك امرؤ فيك جاهلية قال إنهم إخوانكم فضلكم الله عليهم فمن لم يلائمكم فبيعوه ولا تعذبوا خلق الله
No references are available.
Bukhari narrated it in "al-Adab," the chapter on what is forbidden of cursing and insulting, no. 6050, and Muslim in "al-Iman," the chapter on feeding the slave from what one eats, no. 1661, from the hadith of Amash by the same chain.