Musnad Ahmad 1153:1528

'Abd al-Rahman ibn Mahdi narrated to us, from Mu'awiyah—meaning Ibn Salih—from 'Abdullah ibn Abi Qays, who said: I asked 'Aishah about the two rak'ahs after the 'Asr prayer. She said: "The Prophet, peace and blessings of Allah be upon him, used to pray two rak'ahs after the Dhuhr prayer, but he was distracted from them until he prayed the 'Asr. When he finished, he prayed them in my house, and he did not abandon them until he died." 'Abdullah ibn Abi Qays said: I asked Abu Hurayrah about them, and he said: "We used to do that, then we abandoned it."