Two young men got into a fight, one from the Emigrants and one from the Helpers. The Emigrant, or the Emigrants, called out, "Help, Emigrants!"The Helper called out, "Help, Helpers!"The Messenger of Allah ﷺ came out and said, "What is this call of the days of ignorance?"They replied, "Nothing, Messenger of Allah, except that two young men got into a fight and one of them kicked the other from behind."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 support for him. If he is wronged, let him aid him."
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.
Muslim narrated it in "Righteousness and Kinship Ties" (2584), from Ahmad bin Abdullah bin Yunus, who said, Zuhayr told us, Abu Zubayr told us, from Jabir, and he mentioned it.The core of the story is found in the Sahihayn, but they do not contain the Prophet's ﷺ statement, "Then there is no harm, and let the man help..." This is mentioned in its proper place.His saying, "kasaa," means he struck his backside. His saying, "then there is no harm," means that no harm resulted from this incident of the sort I had feared.