Sahih Muslim 6582

حَدَّثَنَا أَحْمَدُ بْنُ عَبْدِ اللَّهِ بْنِ يُونُسَ حَدَّثَنَا زُهَيْرٌ حَدَّثَنَا أَبُو الزُّبَيْرِ عَنْ جَابِرٍ قَالَ اقْتَتَلَ غُلَامَانِ غُلَامٌ مِنْ الْمُهَاجِرِينَ وَغُلَامٌ مِنْ الْأَنْصَارِ فَنَادَى الْمُهَاجِرُ أَوْ الْمُهَاجِرُونَ يَا لَلْمُهَاجِرِينَ وَنَادَى الْأَنْصَارِيُّ يَا لَلْأَنْصَارِ فَخَرَجَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فَقَالَ مَا هَذَا دَعْوَى أَهْلِ الْجَاهِلِيَّةِ قَالُوا لَا يَا رَسُولَ اللَّهِ إِلَّا أَنَّ غُلَامَيْنِ اقْتَتَلَا فَكَسَعَ أَحَدُهُمَا الْآخَرَ قَالَ فَلَا بَأْسَ وَلْيَنْصُرْ الرَّجُلُ أَخَاهُ ظَالِمًا أَوْ مَظْلُومًا إِنْ كَانَ ظَالِمًا فَلْيَنْهَهُ فَإِنَّهُ لَهُ نَصْرٌ وَإِنْ كَانَ مَظْلُومًا فَلْيَنْصُرْهُ

Jabir b. Abdullah reported that two young men, one from the Muhajirin (emigrants) and the other one from the Angr (helpers) fell into dispute and the Muhajir called his fellow Muhajirin, and the Ansari (the helper) called the Ansar (for help). In the meanwhile, Allah's Messenger ( ‌صلی ‌اللہ ‌علیہ ‌وسلم ‌ ) came there and said: What is this, the proclamation of the days of jahiliya (ignorance)? They said: Allah's Messenger, there is nothing serious. The two young men fell into dispute and the one struck at the back of the other. Thereupon he (the Holy Prophet) said: Well, a person should help his brother whether he is an oppressor or an oppressed. If he is the oppressor he should prevent him from doing it, for that is his help; and if he is the oppressed he should be helped (against oppression).