Nafi' (may Allah have mercy on him) said: When Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) was asked about the fear prayer, he would say: The imam goes forward along with a group; then he narrated the hadith. Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) said: "If the fear is more severe, then pray standing or riding, whether facing the qiblah or not." Nafi' (may Allah have mercy on him) said: In my view, Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrated this only from the Prophet (peace and blessings be upon him).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب صلاة الخوف / 6023