Muwatta Imam Malik Book of Jihad, Hadith 32

Yahya related to me from Malik from Abu'n-Nadr, the mawla of Umar ibn Ubaydullah that he had heard that the Messenger of Allah ﷺ said over the martyrs of Uhud, "I testify for them." Abu Bakr as-Siddiq said, "Messenger of Allah! Are we not their brothers? We entered Islam as they entered Islam and we did jihad as they did jihad." The Messenger of Allah ﷺ said, "Yes, but I do not know what you will do after me." Abu Bakr wept profusely and said, "Are we really going to out-live you!"

وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ أَبِي النَّضْرِ، مَوْلَى عُمَرَ بْنِ عُبَيْدِ اللَّهِ أَنَّهُ بَلَغَهُ أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ لِشُهَدَاءِ أُحُدٍ " هَؤُلاَءِ أَشْهَدُ عَلَيْهِمْ " . فَقَالَ أَبُو بَكْرٍ الصِّدِّيقُ أَلَسْنَا يَا رَسُولَ اللَّهِ بِإِخْوَانِهِمْ أَسْلَمْنَا كَمَا أَسْلَمُوا وَجَاهَدْنَا كَمَا جَاهَدُوا . فَقَالَ رَسُولُ اللَّهِ ﷺ " بَلَى وَلَكِنْ لاَ أَدْرِي مَا تُحْدِثُونَ بَعْدِي " . فَبَكَى أَبُو بَكْرٍ ثُمَّ بَكَى ثُمَّ قَالَ أَئِنَّا لَكَائِنُونَ بَعْدَكَ