It is narrated from Sayyiduna Ibn Umar (may Allah be pleased with them both) that I performed two rak'ahs (units of prayer) with the Prophet (peace and blessings be upon him) at Mina, and with the two Shaykhs (may Allah be pleased with them), and also during the early days of the caliphate of Sayyiduna Uthman (may Allah be pleased with him), I performed only two rak'ahs with him as well. Later, Sayyiduna Uthman (may Allah be pleased with him) started to complete (the prayer to four rak'ahs).