Musnad Abu Ya'la al-Mawsili 151:12

Abu Bakr narrated to us, Abd al-Rahim narrated to us, from Layth ibn Abi Sulaym, from Abd al-Rahman ibn al-Aswad, from his father, from Abdullah ibn Mas'ud, who said: I went out with the Messenger of Allah, may Allah bless him and grant him peace, for a need. He said: "Bring me something with which I may cleanse myself (istinja), and do not bring me any bone or dung."