Musnad Ahmad 1156:179

Muhammad ibn Ja‘far narrated to us, he said: Shu‘bah narrated to us, from Yazid ibn Abi Ziyad, who said: I asked ‘Abdullah ibn al-Harith about the two rak‘ahs after the ‘Asr prayer. He said: We were with Mu‘awiyah, and Ibn al-Zubayr narrated from ‘Aishah that the Prophet, peace and blessings of Allah be upon him, used to pray them. So Mu‘awiyah sent [a messenger] to ‘Aishah, and I was among them, and we asked her. She said: "I did not hear it from the Prophet, peace and blessings of Allah be upon him, but Umm Salamah told me." So I asked her [Umm Salamah], and Umm Salamah narrated that the Prophet, peace and blessings of Allah be upon him, prayed Dhuhr, then something was brought to him, and he began to distribute it until the time for the ‘Asr prayer arrived. He stood up and prayed ‘Asr, then he prayed two rak‘ahs after it. When he had prayed them, he said: "These two rak‘ahs are what I used to pray after Dhuhr." Umm Salamah said: "And I had told him that the Messenger of Allah, peace and blessings of Allah be upon him, forbade them." He said: So I came to Mu‘awiyah and informed him of that. Ibn al-Zubayr said: "Did he not pray them? I will not cease praying them." Mu‘awiyah said to him: "You are indeed a dissenter; you will not cease to love dissent as long as you remain."