Musnad Ahmad 788:156

Isma'il narrated to us, Layth informed us, from Abu Burdah ibn Abi Musa, from his father, that he said: A funeral procession passed by the Messenger of Allah, may Allah bless him and grant him peace, [moving] with a jolting motion like the jolting of a waterskin. The Messenger of Allah, may Allah bless him and grant him peace, said: "You must maintain moderation."