Musnad Ahmad 33:811

'Affan narrated to us, Aban narrated to us, Yahya ibn Abi Kathir narrated to us, from Abu Salamah ibn 'Abd al-Rahman, from Jabir ibn 'Abd Allah, who said: We arrived with the Messenger of Allah, may Allah bless him and grant him peace, until we were at Dhat al-Riqa'. He said: When we would come upon a shady tree, we would leave it for the Messenger of Allah, may Allah bless him and grant him peace. Then a man from the polytheists came, and the sword of the Messenger of Allah, may Allah bless him and grant him peace, was hanging on a tree. He took the sword of the Prophet of Allah, may Allah bless him and grant him peace, and drew it. Then he said to the Messenger of Allah, may Allah bless him and grant him peace: "Do you fear me?" He said: "No." He said: "Then who will protect you from me?" He said: "Allah will protect me from you." He said: Then the companions of the Messenger of Allah, may Allah bless him and grant him peace, threatened him, so he sheathed the sword and hung it up. Then the call to prayer was made, so he prayed two rak'ahs with one group, and they stepped back, and he prayed two rak'ahs with the other group. Thus, there were four rak'ahs for the Messenger of Allah, may Allah bless him and grant him peace, and two rak'ahs for the people.