Musnad Ahmad 435:30

Ya'qub narrated to us, my father narrated to us, from Ibn Ishaq, Yahya ibn 'Abbad ibn 'Abdullah ibn al-Zubayr narrated to us, from his father 'Abbad, who said: When Mu'awiyah came to us for Hajj, we came with him to Makkah. He said: He prayed the Dhuhr prayer with us as two rak'ahs, then he departed to Dar al-Nadwah. He said: 'Uthman, when he completed the prayer, used to pray the Dhuhr, 'Asr, and the final 'Isha' as four rak'ahs each when he came to Makkah. When he went out to Mina and 'Arafat, he would shorten the prayer. When he finished the Hajj and stayed in Mina, he would complete the prayer until he left Makkah. When Mu'awiyah prayed the Dhuhr with us as two rak'ahs, Marwan ibn al-Hakam and 'Amr ibn 'Uthman stood up to him and said to him: "No one has criticized your cousin more severely than you have criticized him." He said to them: "And what is that?" He said: They said to him: "Do you not know that he completed the prayer in Makkah?" He said: He said to them: "Woe to you! Was there anything other than what I have done? I have prayed them with the Messenger of Allah (peace and blessings of Allah be upon him), and with Abu Bakr and 'Umar (may Allah be pleased with them both)." They said: "But your cousin used to complete it, and your differing from him is a criticism of him." He said: "So Mu'awiyah went out for the 'Asr and prayed it with us as four rak'ahs."