Allah Almighty says: «‏‏‏‏فَإِنْ خِفْتُمْ فَرِجَالًا أَوْ رُكْبَانًا» ‏‏‏‏ [ سورة البقرة: 239 ] "Then if you are in a state of fear, pray on foot or while riding."

It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that when he was asked about the prayer of fear (Salat al-Khawf), he would narrate a lengthy hadith and say: Then, if the fear becomes even more severe, you should pray standing on your feet or riding, facing the Qiblah or not facing the Qiblah. Nafi’ narrates that Sayyiduna Ibn Umar (may Allah be pleased with them both) narrated this from the Messenger of Allah (peace and blessings be upon him). Imam Abu Bakr (may Allah have mercy on him) says that when the students of Imam Malik narrated this from him, he said: Nafi’ said,“In my opinion, Sayyiduna Ibn Umar (may Allah be pleased with them both) narrates this from the Messenger of Allah (peace and blessings be upon him).”