Musnad Ahmad 788:128

Muhammad ibn Ja‘far narrated to us, Shu‘bah narrated to us, from Layth, who said: I heard Abu Burdah narrating from his father, who said: Some people passed by the Messenger of Allah, may Allah bless him and grant him peace, with a funeral procession, and they were hastening with it. The Messenger of Allah, may Allah bless him and grant him peace, said: "Let there be upon you tranquility."