Sayyiduna Abd al-Rahman bin Abi Bakr (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "Bring me an inkpot and a shoulder (bone of an animal), so that I may write for you a document after which you will never go astray." The narrator says: Then he turned his back to us, then he turned towards us and said: "Allah Almighty and the believers will accept none but Abu Bakr."
Al-Tabarani recorded it; its chain contains a narrator whom I do not know.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الخلافة / 8930