Sahih al-Bukhari 3658
Narrated `Abdullah bin Abi Mulaika:
The people of Kufa sent a letter to Ibn Az-Zubair, asking about (the inheritance of) (paternal) 
grandfather. He replied that the right of the inheritance of (paternal) grandfather is the same as that of 
father if the father is dead) and added, "Allah's Messenger (ﷺ) said, ' If I were to take a Khalil from this 
nation, I would have taken him (i.e. Abu Bakr).
حَدَّثَنَا سُلَيْمَانُ بْنُ حَرْبٍ، أَخْبَرَنَا حَمَّادُ بْنُ زَيْدٍ، عَنْ أَيُّوبَ، عَنْ عَبْدِ اللَّهِ بْنِ أَبِي مُلَيْكَةَ، قَالَ كَتَبَ أَهْلُ الْكُوفَةِ إِلَى ابْنِ الزُّبَيْرِ فِي الْجَدِّ‏.‏ فَقَالَ أَمَّا الَّذِي قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏
"‏ لَوْ كُنْتُ مُتَّخِذًا مِنْ هَذِهِ الأُمَّةِ خَلِيلاً لاَتَّخَذْتُهُ ‏"‏‏.‏ أَنْزَلَهُ أَبًا يَعْنِي أَبَا بَكْرٍ‏.‏