Musnad Ahmad 957:4

'Affan narrated to us, 'Abd al-Wahid ibn Ziyad narrated to us, Mansur ibn Hayyan narrated to us, Sulayman al-Khuza'i narrated to me, from his maternal uncle Malik ibn 'Abd Allah, who said: "I went on a military expedition with the Messenger of Allah, may Allah bless him and grant him peace, and I never prayed behind an Imam leading the people who had a lighter prayer than the Messenger of Allah, may Allah bless him and grant him peace."