Sahih al-Bukhari 4907

It is related that Jabir ibn 'Abdullah said, "We were on an expedition (and Sufyan once said, "In an army") and a man of the Muhajirun kicked a man of the Ansar on his buttocks. The Ansari man exclaimed, 'Ansar! Help!' The Muhajir man said, 'O Muhajirun! Help!' The Messenger of Allah, may Allah bless him and grant him peace, heard that and said, 'What is this?!' They said, 'Messenger of Allah, a man of the Muhajirun kicked one of the Ansar on the buttocks! and so the Ansari said, "Ansar! Help!" and the Muhajir said "O Muhajirun! Help!" The Prophet, may Allah bless him and grant him peace, said, 'Leave it (the summons). It is vile.'" Jabir said, "The Ansar were more numerous when the Prophet, may Allah bless him and grant him peace, arrived and then aftr that the Muhajirun increased in number. 'Abdullah ibn Ubayy said, 'They have done that? By Allah, if we return to Madina, then the mightier will expel the more humble from it.' 'Umar ibn al-Khattab said, 'Messenger of Allah! Let me cut off the head of this hypocrite!' The Prophet, may Allah bless him and grant him peace, said, 'Leave him. People will not say that Muhammad kills his Companions.'"