Yazid bin Ruman told on the authority of Salih bin Khawwat on the authority of one who prayed in time of danger with Allah's Messenger (may peace he upon him) at the Battle of Dhat ar-Riqa' that a group formed a row and prayed along with him, and a group faced the enemy. He led the group which was along with him in a rak'ah, then remained standing while they finished the prayer by themselves. Then they departed and formed a row facing the enemy. Then the second group came and he led them in the remaining rak'ah, after which he remained seated while they finished the prayer themselves. He then led them in salutation.
Hadith Referenceصحيح مسلم / کتاب فضائل القرآن وما يتعلق به / 842
Hadith Commentary:Benefits and Issues: The first group joined the Prophet (sallallahu alayhi wa sallam) in the opening takbir (takbir al-tahrimah) and participated in the first rak‘ah with him; they performed the second rak‘ah and the salam on their own. The second group joined the Prophet (sallallahu alayhi wa sallam) in his second rak‘ah and in the salam, and performed one rak‘ah on their own. Salih bin Khawat narrated this report from his father, Khawat bin Jubayr (radi Allahu anhu), as clarified by Imam Ibn Mandah, and this is mentioned in Bulugh al-Maram.
Source: Tuhfat al-Muslim: Commentary on Sahih Muslim, Page: 1948
´It was narrated from Salih bin Khawwat from one who had prayed the fear prayer with the Messenger of Allah (ﷺ) on the day of Dhat Ar-Riqa' that:` One group had formed a row behind him and another group faced the enemy. He led those who were with him in praying one rak'ah, then he remained standing and they completed the prayer by themselves. Then they moved away and formed a row facing the enemy, and the other group came and he led them in praying the rak'ah that was left for him, then he remained sitting while they completed the prayer by themselves, then he said the taslim with them.
Hafiz Muhammad Ameen
1538. Commentary:
➊ This is another form of the prayer of fear (salat al-khawf) in which each group prays two units (rak‘ahs) together—one with you and one separately. This form is preferable in that there will be no coming and going during the prayer; rather, both units will be performed consecutively.
➋ "Dhat al-Riqa‘": "Riqa‘" is the plural of "riq‘ah," which means: a piece (of cloth). This battle is called the Expedition of Dhat al-Riqa‘ either because, while going for this expedition, the Muslims’ feet were wounded due to the stones and they had to tie pieces of cloth on their feet, or because the land of that area consisted of patches of different colors—that is, some hills were red, some white, and some black. And Allah knows best.
Source: Sunan Nasa'i: Translation and Benefits by Shaykh Hafiz Muhammad Amin Hafizullah, Page: 1538