Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) says: The Prophet (peace and blessings be upon him) went off to relieve himself and said: "Bring me something with which I may clean myself (istinja), and do not bring me a bone or dung." I did so, then he (peace and blessings be upon him) performed ablution and prayed.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 9922