Sahih Bukhari
Companions of the Prophet
Volume: 005 / Book Number: 057 / Hadith Number: 10
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 Apostle said, ' If I were to take a Khalil from this nation, I would have taken him (i.e. Abu Bakr)."