Sahih Ibn Khuzaymah

Sayyiduna Sahl bin Abi Hathmah (may Allah be pleased with him), while describing the manner of the prayer of fear (Salat al-Khawf), says that the Imam will stand facing the Qiblah and a group of Muslims will stand with him, while the other group will stand facing the enemy. Thus, the Imam will lead the first group in one rak‘ah. In the narration of Abu Musa, it is mentioned that then they will stand and perform ruku‘. And in the narration of Bundar, the words are as follows: they will perform ruku‘ themselves and perform two prostrations for themselves in their place. Then this group will move to the place of the other group. That group will come, and the Imam will lead them in one ruku‘ and two prostrations. In this way, the Imam will have completed two rak‘ahs and they will have completed one rak‘ah; then they will complete their second rak‘ah. In the narration of Abu Musa, it is mentioned that they will perform one rak‘ah with two prostrations for themselves. This is the narration of Bundar except for those words in which Abu Musa differed from him; I have mentioned them. Abu Musa has only mentioned the words "li-anfusihim" (they will perform for themselves) in two places. Imam Abu Bakr (may Allah have mercy on him) says that I heard Bundar (may Allah have mercy on him) say that I asked Imam Yahya about this hadith, so he narrated this hadith to me from Shu‘bah (may Allah have mercy on him).