Musnad Abu Ya'la al-Mawsili 216:8

Daud ibn Rashid narrated to us, Abbad ibn al-Awwam narrated to us, Hanzalah al-Sadusi narrated to us, he said: I heard Abdullah ibn al-Harith ibn Nawfal narrating that Maymunah said: The Messenger of Allah, may Allah bless him and grant him peace, used to pray two rak'ahs before the Asr prayer. She said: And the Messenger of Allah, may Allah bless him and grant him peace, whenever he performed a prayer, he liked to be constant in it.