Sahih Bukhari, Chapter: Wills and Testaments (Wasaya)

The Prophet (SAW) said to Abu Talha, "Give (your garden) to the poor amongst your relatives." So he gave it to Hassan and Ubai bin Kab. Anas added in another narration, "So he gave it to Hassan and Ubai bin Kab who were nearer relatives to him than I." The relation between Hassan and Ubai to Abu Talha was as follows: Abu Talha's name was Zaid, the son of Sahl, the son of Al-Aswad, the son of Haram, the son Amr, the son of Zaid Manat, the son of Adi, the son of Amr, the son of Malik, the son of An-Najjar. Hassan was the son of Thabit, the son of Al-Mundhir, the son of Haram, this means that Talha and Hassan had a common great grandfather (i.e., Haram, the third in the line of descent). Hassan and Abu Talha and Ubai had a common ancestor, Amr bin Malik, the sixth in the lineage, as Ubai was the son of Kab, the son of Qais, the son of Ubaid, the son of Zaid, the son of Muawiya, the son of Amr, the son of Malik, the son of An-Najjar. Some scholars say, "If one wants to will some of his wealth to one's relatives, they must be among those who share a Muslim common ancestor with one."