Sahih Muslim Book 013, Hadith Number 4015.
Chapter : He who has not anything with him to will away should not do it.
Sa'id b. Jubair reported from Ibn Abbas that he said: Thursday, and what about Thursday? Then tears began to flow until I saw them on his cheeks as it they were the strings of pearls. He (the narrator) said that Allah's Messenger (may peace be upon him) said: Bring me a shoulder blade and ink-pot (or tablet and inkpot), so that I write for you a document (by following which) you would never go astray. They said: Allah's Messenger (may peace upon him) is in the state of unconsciousness.