Musnad Ahmad 1153:628

'Affan narrated to us, he said: Wuhayb narrated to us, he said: Hisham ibn 'Urwah narrated to us, from his father, from 'Aishah, that she said: "By Allah, the Messenger of Allah (may Allah bless him and grant him peace) never once left the two rak'ahs after the 'Asr prayer while in my presence."