Musannaf Ibn Abi Shaybah

It is narrated from Hazrat Ibn Umar (may Allah be pleased with them both) that the Noble Prophet (peace and blessings be upon him) performed two rak‘ahs in Mina. Then after him, Hazrat Siddiq Akbar performed two rak‘ahs, then after Siddiq Akbar, Hazrat Umar performed two rak‘ahs, and Hazrat Uthman, in the early years of his caliphate, performed two rak‘ahs. Then Hazrat Uthman began to perform four rak‘ahs. Hazrat Ibn Umar (may Allah be pleased with them both), when performing with the imam, would perform four rak‘ahs, and if he prayed alone, he would perform two rak‘ahs.