It is narrated from the Mother of the Believers, Sayyidah Aishah (may Allah be pleased with her), that she said: The Messenger of Allah (peace and blessings be upon him) said to me: "Call your father and your brother so that I may write a document, for I fear that someone (claiming the caliphate) may say something and someone may wish (for it), whereas Allah Almighty and the believers will accept no one but Sayyiduna Abu Bakr (may Allah be pleased with him)."
No one narrated this hadith from al-Zuhri (may Allah have mercy on him) except Salih bin Kaysan (may Allah have mercy on him), and from Salih bin Kaysan (may Allah have mercy on him) only Ibrahim bin Sa'd (may Allah have mercy on him) narrated it, while Yazid bin Harun (may Allah have mercy on him) and Ahmad bin Muhammad bin Ayyub (may Allah have mercy on him) are alone in narrating it.
Hadith Referenceالمعجم الأوسط / باب الميم / 6571
Hadith Takhrij«أخرجه مسلم فى «صحيحه» برقم: 2387، وابن حبان فى «صحيحه» برقم: 6598، والنسائي فى «السنن الكبرى» برقم: 7044، والبيهقي فى «السنن الكبرى» برقم: 16685، وأحمد فى «مسنده» برقم: 25390، 25753، والطبراني فى «الأوسط» برقم: 4331، 4567»