Jabir reported, "We were on a military expedition when a man from the Muhajirun kicked a man from the Ansar from behind. The Ansari called out, 'Help, Ansar!' and the Muhajiri called out, 'Help, Muhajirun!'The Messenger of Allah ﷺ heard this and asked, 'What is going on?'They said, 'A man from the Muhajirun kicked a man from the Ansar, so the Ansari called out, 'Help, Ansar!' and the Muhajiri called out, 'Help, Muhajirun!'The Prophet ﷺ said, 'Leave such calls aside, for they are rotten.'"Jabir continued, "When the Prophet ﷺ first arrived in Medina, the Ansar were more numerous, but later the Muhajirun grew in number. Abdullah bin Ubayy said, 'So they have done that, have they? By Allah, when we return to Medina, the mightier among us will surely drive out the weaker.'Umar bin Khattab said, 'Messenger of Allah, let me strike off the head of this hypocrite.'The Prophet ﷺ replied, 'Leave him be, lest people say that Muhammad kills his own companions.'"
كنا في غزاة فكسع رجل من المهاجرين رجلا من الأنصار، فقال الأنصاري: يا للأنصار. وقال المهاجري: يا للمهاجرين. فسمعها الله رسوله، فقال: ما هذا؟ فقالوا: كسع رجل من المهاجرين رجلا من الأنصار، فقال الأنصاري: يا للأنصار. وقال المهاجري: يا للمهاجرين. فقال النبي ﷺ: دعوها؛ فإنها منتنة قال جابر: وكانت الأنصار حين قدم النبي ﷺ أكثر، ثم كثر المهاجرون بعد، فقال عبد الله بن أبي: أو قد فعلوا والله لئن رجعنا إلى المدينة ليخرجن الأعز منها الأذل، فقال عمر بن الخطاب: دعني يا رسول الله، أضرب عنق هذا المنافق. فقال النبي ﷺ: دعه، لا يتحدث الناس أن محمدا يقتل أصحابه.
Bukhari narrated it in the tafsir (4907), and Muslim in "Piety, Kinship, and Manners" (2584:63), both through the route of Sufyan bin Uyayna, who said, "We memorized it from Amr bin Dinar," who said, "I heard Jabir bin Abdullah say," then he mentioned it, and the wording given is Bukhari's. His statement, "kasaa," means he struck him on his backside.