Jabir bin Abdullah reported,

Two young men got into a fight, one from the Muhajirun and one from the Ansar. The Muhajiri, or perhaps the Muhajirun collectively, called out, "Help, Muhajirun!" and the Ansari called out, "Help, Ansar!"The Messenger of Allah ﷺ came out and asked, "What is this, the call of the days of ignorance?"They replied, "No, Messenger of Allah, it is only that two young men got into a fight and one of them kicked the other."He said, "There is no harm in that. Let a man support his brother whether he is the wrongdoer or the wronged. If he is the wrongdoer, let him restrain him, for that is supporting him, and if he is wronged, let him aid him."

Azami 15015

Sahih

عن جابر، قال

اقتتل غلامان غلام من المهاجرين، وغلام من الأنصار، فنادى المهاجر أو المهاجرون، يا للمهاجرين ونادى الأنصاري يا للأنصار، فخرج رسول الله ﷺ فقال: ما هذا دعوى أهل الجاهلية قالوا: لا يا رسول الله إلا أن غلامين اقتتلا فكسع أحدهما الآخر، قال: فلا بأس ولينصر الرجل أخاه ظالما أو مظلوما، إن كان ظالما فلينهه، فإنه له نصر وإن كان مظلوما فلينصره.

الأعظمي 15015صحيح
Contents
Reference
Commentary
Ayat
Collection
Jami al-Kamil
Book
Superior moral conduct
Chapter
Vices of character
Section
Condemnation of tribalism
Numbering
Jami al-Kamil 15015 (2nd edition)
Azami 15015