Musnad Ahmad 938:17

Waki’ narrated to us, Sufyan narrated to us, from Abu Bakr ibn Abi al-Jahm ibn Sukhayr, from Ubaydullah ibn Utbah, from Ibn Abbas, who said: "The Messenger of Allah (ﷺ) performed the prayer of fear at Dhu Qard, a land from the lands of Banu Sulaym. He arranged the people behind him in two rows: a row parallel to the enemy, and a row behind him. He prayed one rak'ah with the row that was next to him. Then, those [in the first row] retreated to the positions of those [in the second row], and those [in the second row] moved to the positions of those [in the first row], and he prayed another rak'ah with them."