If somebody founds an endowment (or bequeathes) his relatives by a will

وَقَالَ ثَابِتٌ عَنْ أَنَسٍ قَالَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ لأَبِي طَلْحَةَ: «اجْعَلْهَا لِفُقَرَاءِ أَقَارِبِكَ». فَجَعَلَهَا لِحَسَّانَ وَأُبَيِّ بْنِ كَعْبٍ. وَقَالَ الأَنْصَارِيُّ حَدَّثَنِي أَبِي، عَنْ ثُمَامَةَ، عَنْ أَنَسٍ، مِثْلَ حَدِيثِ ثَابِتٍ قَالَ ‏"‏ اجْعَلْهَا لِفُقَرَاءِ قَرَابَتِكَ ‏"‏‏.‏ قَالَ أَنَسٌ فَجَعَلَهَا لِحَسَّانَ وَأُبَىِّ بْنِ كَعْبٍ، وَكَانَا أَقْرَبَ إِلَيْهِ مِنِّي، وَكَانَ قَرَابَةُ حَسَّانَ وَأُبَىٍّ مِنْ أَبِي طَلْحَةَ وَاسْمُهُ زَيْدُ بْنُ سَهْلِ بْنِ الأَسْوَدِ بْنِ حَرَامِ بْنِ عَمْرِو بْنِ زَيْدِ مَنَاةَ بْنِ عَدِيِّ بْنِ عَمْرِو بْنِ مَالِكِ بْنِ النَّجَّارِ، وَحَسَّانُ بْنُ ثَابِتِ بْنِ الْمُنْذِرِ بْنِ حَرَامٍ فَيَجْتَمِعَانِ إِلَى حَرَامٍ، وَهْوَ الأَبُ الثَّالِثُ، وَحَرَامُ بْنُ عَمْرِو بْنِ زَيْدِ مَنَاةَ بْنِ عَدِيِّ بْنِ عَمْرِو بْنِ مَالِكِ بْنِ النَّجَّارِ، فَهْوَ يُجَامِعُ حَسَّانُ أَبَا طَلْحَةَ وَأُبَىٌّ إِلَى سِتَّةِ آبَاءٍ إِلَى عَمْرِو بْنِ مَالِكٍ، وَهْوَ أُبَىُّ بْنُ كَعْبِ بْنِ قَيْسِ بْنِ عُبَيْدِ بْنِ زَيْدِ بْنِ مُعَاوِيَةَ بْنِ عَمْرِو بْنِ مَالِكِ بْنِ النَّجَّارِ، فَعَمْرُو بْنُ مَالِكٍ يَجْمَعُ حَسَّانَ وَأَبَا طَلْحَةَ وَأُبَيًّا‏.‏ وَقَالَ بَعْضُهْمْ إِذَا أَوْصَى لِقَرَابَتِهِ فَهْوَ إِلَى آبَائِهِ فِي الإِسْلاَمِ‏.‏Narrated Anas رضي الله عنه: The Prophet ﷺ said to Abu Talha, "Give (your garden) to the poor amongst your relatives." So he gave it to Hassan and Ubai bin Ka'b. Anas added in another narration, "So he gave it to Hassan and Ubai bin Ka'b 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 of 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 Abu 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 Ka’b, the son of Qais, the son of Ubaid, the son of Zaid, the son of Mu'awiya, 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."