An Nasai

"We were with Sa'eed bin Al-'Asi in Tabaristan, and Hudhaifah bin Al-Yaman was with us. He said: 'Which of you offered the fear prayer with the Messenger of Allah (ﷺ)?' Hudhaifah said: 'I did', and he described it. He said: 'The Messenger of Allah (ﷺ) offered the fear prayer, leading one group who had formed rows behind him in praying one rak'ah, while the other group was between him and the enemy. So he led the group that was near him in praying one rak'ah, then they left and took the place of others, and the others came and he led them in praying one rak'ah.'"

"We were with Sa'eed bin Al-'Asi in Tabaristan, and Hudhaifah bin Al-Yaman was with us. He said: 'Which of you offered the fear prayer with the Messenger of Allah (ﷺ)?' Hudhaifah said: 'I did.' So Hudhaifah stood and the people formed two rows behind him, one row behind him and one row facing the enemy. He led those who were behind him in praying one rak'ah, then they went and took the place of the others, and the others came and he led them in praying one rak'ah, and they did not make it up."

A prayer like that of Hudhaifah was narrated from Zaid bin Thabit from the Prophet (ﷺ).

"Allah (SWT) enjoined the prayer on the tongue of your Prophet (ﷺ): four (rak'ahs) while a resident, two rak'ahs while traveling, and one rak'ah during times of fear."

The Messenger of Allah (ﷺ) prayed at Dhi Qarad and the people formed two rows behind him, one row behind him and one row facing the enemy. He led those who were behind him in praying one rak'ah, then they went and took the place of the others, and the others came and he led them in praying one rak'ah, and they did not make it up.

Abdullah bin 'Abbas said: "The Messenger of Allah (ﷺ) stood and the people stood with him, and he said the takbir and they said the takbir. Then he bowed, and some of them bowed, then he prostrated and they prostrated, then he stood for the second rak'ah and those who had prostrated with him moved back and guarded their brothers, and the other group came and bowed and prostrated with the Prophet (ﷺ). All the people were praying and saying the takbir, but they were guarding one another."

"The fear prayer was no more than two prostrations like the prayer of these guards of yours today behind the Imams of yours, except that it was one group after another. One group stood, although they were all behind the Messenger of Allah (ﷺ), and one group prostrated with him, then the Messenger of Allah (ﷺ) stood up and they all stood with him. Then he bowed and they all bowed with him, then he prostrated and those who had been standing the first time prostrated with him. When the Messenger of Allah (ﷺ) and those who had prostrated with him at the end of their prayer sat, those who had been standing prostrated by themselves, then they sat and the Messenger of Allah (ﷺ) said the taslim with all of them.

The Messenger of Allah (ﷺ) led them in offering the fear prayer. Some formed a row behind him and some formed a row facing the enemy. He led them in praying one rak'ah, then they moved away and the others came, and he led them in praying one rak'ah, then they got up and each (group) made up the other rak'ah.

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.