Tha’labah bin Zahdam says that once we were in Tabaristan with Sa’id bin ‘As (may Allah be pleased with him). He asked the people,“Who among you has performed the Salat al-Khawf (prayer of fear) with the Prophet Muhammad (peace and blessings be upon him)?”Hudhayfah (may Allah be pleased with him) replied,“I have.”Then he ordered the people, so they put on their weapons. Hudhayfah (may Allah be pleased with him) then said,“If the enemy suddenly attacks you, it is permissible for you to fight.”Then he led one group in one rak’ah (unit of prayer). One row stood facing the enemy. Then these people (who prayed) retreated backwards to the place of those who were standing in front of the enemy, and those people came and stood behind the Prophet Muhammad (peace and blessings be upon him), and the Prophet Muhammad (peace and blessings be upon him) led them in the second rak’ah. Then the Prophet Muhammad (peace and blessings be upon him) concluded the prayer with salam.