Who specifically constitutes 'Dhawi al-Qurba' (the near relatives) entitled to the share designated for them?

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The 'Dhawi al-Qurba' are exclusively Banu Hashim and Banu al-Muttalib, excluding all others. This is established by the tradition of Jubayr ibn Mut'im, who reported that when the Messenger of Allah (peace be upon him) divided the share of Dhawi al-Qurba from Khaybar between Banu Hashim and Banu al-Muttalib, he and Uthman ibn Affan questioned why Banu al-Muttalib received a share while they (who were of Banu Abd Shams, related through Abd Manaf) were excluded, asserting they were equally related. The Prophet (peace be upon him) replied, affirming that Banu Hashim and Banu al-Muttalib are one entity, and further stating, 'They did not separate from us in ignorance (Jahiliyyah) nor in Islam.' This indicates that the entitlement is based on their unwavering support and affiliation with Banu Hashim throughout both eras. This narration is reported by Ahmad and Al-Bukhari.