Musnad Abu Ya'la al-Mawsili 115:149

Ahmad ibn al-Miqdam narrated to us, Mu'tamir narrated to us, my father narrated to us, from Qatadah, from Anas, who said: The general part of the final instruction of the Messenger of Allah (may Allah bless him and grant him peace) when death approached him was: "The prayer, and what your right hands possess." He continued repeating it until his chest rattled with it, and his tongue could no longer utter it.