Yahya related to me from Malik from Abu'n-Nadr, the mawla of Umaribn Ubaydullah that he had heard that the Messenger of Allah, mayAllah bless him and grant him peace, said over the martyrs of Uhud, "Itestify for them." Abu Bakr as-Siddiq said, "Messenger of Allah! Arewe not their brothers? We entered Islam as they entered Islam and wedid jihad as they did jihad." The Messenger of Allah, may Allah blesshim and grant him peace, said, "Yes, but I do not know what you willdo after me." Abu Bakr wept profusely and said, "Are we really goingto out-live you!"
USC-MSA web (English) reference: Book 21, Hadith 32
Arabic reference: Book 21, Hadith 993