Musnad Abu Ya'la al-Mawsili 49:2

Abu Bakr narrated to us, Abd al-Wahhab al-Thaqafi narrated to us, from Abdullah ibn Uthman, from Nafi ibn Sarjas Abu Sa’id, that he heard Abu Waqid al-Laythi, a companion of the Messenger of Allah (may Allah bless him and grant him peace), and prayer was mentioned in his presence. He said: "The Messenger of Allah (may Allah bless him and grant him peace) was the lightest of people in prayer for the people, and the most constant of them in it for himself."