Musnad Ahmad Hadith 16580

It is narrated from Abu Ayyash Zarqi (may Allah be pleased with him) that once we were with the Prophet (peace and blessings of Allah be upon him) at the place of Usfan when the polytheists appeared coming from the front. Their leader was Khalid bin Walid. They were positioned between us and the Qiblah. During this time, the Prophet (peace and blessings of Allah be upon him) began to lead us in the Zuhr prayer. Seeing this, the polytheists said, "In the state they are in, if we wanted, we could attack them." Then they themselves said, "Another prayer time is about to come which is dearer to them than their children and even their own lives." At this moment, during the interval between Zuhr and Asr, Jibreel descended with these verses: "And when you are among them...". So when the time for Asr prayer came, the Prophet (peace and blessings of Allah be upon him) ordered the companions and they took up their weapons. Then we formed two rows behind the Prophet (peace and blessings of Allah be upon him). The Prophet (peace and blessings of Allah be upon him) bowed in ruku and we also bowed. When he raised his head from ruku, we also raised our heads. Then the Prophet (peace and blessings of Allah be upon him), along with those in the first row, performed sajdah, while those in the second row stood and kept watch. When they had completed their sajdah and stood up, those behind sat and performed sajdah. Then both rows switched their places and came to each other's positions. In the second rak'ah, all performed ruku together and raised their heads together. After that, the Prophet (peace and blessings of Allah be upon him), along with the row behind him, performed sajdah, while those at the back stood and kept watch. When the Prophet (peace and blessings of Allah be upon him) sat, the second row also sat and performed sajdah. After this, the Prophet (peace and blessings of Allah be upon him) said salam and completed the prayer. The Prophet (peace and blessings of Allah be upon him) led such a prayer twice: once at Usfan and once in an area of Banu Sulaym.