Musnad Ahmad 341:1

'Abd al-Razzaq narrated to us, al-Thawri narrated to us, from Mansur, from Mujahid, from Abu 'Ayyash al-Zuraqi, who said: We were with the Messenger of Allah, may Allah bless him and grant him peace, at 'Usfan when the polytheists confronted us, led by Khalid ibn al-Walid, and they were between us and the Qibla. The Messenger of Allah, may Allah bless him and grant him peace, led us in the Dhuhr prayer. They (the polytheists) said: "They were in a state where, had we attacked them while they were heedless..." Then they said: "A prayer will come upon them now that is dearer to them than their children and their own selves." He said: Then Gabriel, peace be upon him, descended with these verses between Dhuhr and 'Asr: {And when you are among them and lead them in prayer...} [An-Nisa: 102]. He said: When the time for prayer arrived, the Messenger of Allah, may Allah bless him and grant him peace, commanded them, so they took up their weapons. He said: We lined up behind him in two rows. He said: Then he bowed, and we all bowed. Then he rose, and we all rose. Then the Prophet, may Allah bless him and grant him peace, prostrated with the row that was next to him, while the others remained standing, guarding them. When they (the first row) had prostrated and stood up, the others sat down and prostrated in their place. Then those (the first row) moved forward to the position of those (the second row), and those (the second row) came to the position of those (the first row). He said: Then he bowed, and they all bowed. Then he rose, and they all rose. Then the Prophet, may Allah bless him and grant him peace, prostrated with the row that was next to him, while the others remained standing, guarding them. When he sat, the others sat, and they prostrated. Then he greeted them (with Taslim), and then he departed. He said: The Messenger of Allah, may Allah bless him and grant him peace, performed it (the prayer) twice: once at 'Usfan, and once in the land of Banu Sulaym.