It is narrated from Sayyiduna Jabir bin Abdullah, may Allah be pleased with him, that the Noble Prophet, peace and blessings be upon him, led his noble companions in the prayer of fear. He performed the bowing (ruku) with all of them, then the Messenger of Allah, peace and blessings be upon him, and the row closest to him performed the prostration (sajdah), while the second row remained standing. When the Prophet, peace and blessings be upon him, and those in the first row stood up, the people in the second row performed two prostrations by themselves. Then the first row moved back and stood with them, and those from the second row came forward and stood in the first row. The Noble Prophet, peace and blessings be upon him, performed the (second) bowing with all of them. Then the Messenger of Allah, peace and blessings be upon him, and those in the row closest to him performed the prostrations. When they raised their heads from the prostration, the people in the back row also performed the prostrations. In this way, all the people performed the bowing with the Noble Prophet, peace and blessings be upon him, and performed two prostrations by themselves. And the enemy was lined up facing the qiblah.

It is permissible to start the prayer while sitting with the imam in the second row, and it is permissible for those in the first row to start the prayer while standing with the imam.

Sayyiduna Jabir bin Abdullah (may Allah be pleased with him) narrates from the Messenger of Allah (peace and blessings be upon him) regarding the prayer of fear that the Messenger of Allah (peace and blessings be upon him) stood up while one group stood behind the Messenger of Allah (peace and blessings be upon him) and the other group was sitting behind the standing group. All their faces were towards the Messenger of Allah (peace and blessings be upon him). The Messenger of Allah (peace and blessings be upon him) said the takbir, so both groups also said the takbir and began the prayer. Then when he (peace and blessings be upon him) bowed (for ruku‘), the group standing behind him also bowed, while the other group remained sitting. Then when he (peace and blessings be upon him) performed the prostrations, they also performed the prostrations, while the other group remained sitting. Then when he (peace and blessings be upon him) stood up, they also stood up and moved back until they sat in the place of their companions. The other group (came forward), so the Messenger of Allah (peace and blessings be upon him) led them in one rak‘ah with two prostrations, while the other group remained sitting. Then the Messenger of Allah (peace and blessings be upon him) said the salam after the tashahhud. Then both groups stood up and each performed one rak‘ah with two prostrations for themselves (and after tashahhud, said the salam).

And the prayer of the imam with each group is two rak‘ahs, and this is also the type which I have informed of the permissibility of the follower performing an obligatory prayer behind an imam who is praying a voluntary prayer; since one of the two rak‘ahs was for the Prophet, peace and blessings be upon him, a voluntary act, and for the followers an obligation.

Sayyiduna Jabir bin Abdullah (may Allah be pleased with him) narrates that he performed the prayer of fear with the Messenger of Allah (peace be upon him). The Messenger of Allah (peace be upon him) led one group in two rak‘ahs, then led the other group in two rak‘ahs. In this way, the Messenger of Allah (peace be upon him) prayed four rak‘ahs and led each group in two rak‘ahs.

Sayyiduna Jabir bin Abdullah (may Allah be pleased with him) narrates regarding the prayer of fear that the Messenger of Allah (peace and blessings be upon him) led a group of people in two rak‘ahs while the other group was engaged in protection and guarding. Then when the Prophet (peace and blessings be upon him) finished with salam, these worshippers left and the others came, so the Prophet (peace and blessings be upon him) led them also in two rak‘ahs and then finished with salam. Imam Abu Bakr (may Allah have mercy on him) says that our companions among the hadith scholars differ regarding Hasan al-Basri’s hearing from Sayyiduna Jabir (may Allah be pleased with him).

So, after the first group has finished the first rak‘ah, the second group is permitted to abandon facing the qiblah in order to protect against the enemy—and the explanation of both groups completing the second rak‘ah after the imam has said the salām.

It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that the Noble Prophet (peace and blessings be upon him) led them in the prayer of fear (Salat al-Khawf). He led one group, who were standing behind him, in one rak'ah, while another group was standing facing the enemy. Then the group who had prayed got up and stood facing the enemy, and the other group came forward. The Noble Prophet (peace and blessings be upon him) led them in one rak'ah as well, then he said the salam. After that, both groups completed their prayer by praying one rak'ah each.

Imam Sahib has mentioned another chain of narration.

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).