Musannaf Ibn Abi Shaybah 8506 — The fear prayer: how many rakahs it is

Sayyiduna Ibn Umar (may Allah be pleased with them both) said: One day the Prophet (peace and blessings be upon him) led the fear prayer. One group stood with him and one group faced the enemy. The group that was with him prayed one rak'ah, then went off towards the enemy. Then the other group came and he led them in one rak'ah. Then both groups afterwards made up one rak'ah each. Sayyiduna Ibn Umar (may Allah be pleased with them both) said: If the fear of the enemy is even greater than that, then pray by gestures, standing or riding.