Grading: Its chain is sahih, and al-Hafiz Ibn Hajar declared it sahih in "Fath al-Bari" (11/ 148).
Technical note / Identification of the narrator: "Abd al-Wahhab" is Ibn Abd al-Majid al-Thaqafi, "Khalid al-Hadhdha'" is Ibn Mihran, and "Ikrimah" is the freed slave of Ibn Abbas.

Reference / Source: Al-Tirmidhi (3764) and al-Nasa'i (8101) narrated it from Muhammad bin Bashshar, with this same chain. And al-Tirmidhi said: "This hadith is hasan sahih gharib."

Reference / Source: Ahmad (15/ 9353) narrated it by way of Wuhayb bin Khalid, from Khalid al-Hadhdha'. And at its end he said: "Meaning in generosity and nobility (he was the best of people to the poor)."

Details of the narration: This narration will come at number (4998) by way of Ibn Khuzaymah, from Muhammad bin Bashshar.

Reference / Source: Al-Bukhari (5432) narrated by way of Sa'id al-Maqburi from Abu Hurayrah (may Allah be pleased with him) that he said: "The best of people to the poor was Ja'far bin Abi Talib (may Allah be pleased with him). He would take us along and feed us whatever was in his house, to the point that he would bring out to us a skin container of ghee ('ukkah) with nothing in it, and we would split it open and lick what was (left) inside it."

General principle: Al-Hafiz Ibn Hajar says in "al-Fath" (11/ 148): "The unrestricted statement that came in the narration of Ikrimah from Abu Hurayrah is to be understood in light of this restriction (in the narration of Sa'id al-Maqburi, i.e., that he was the best in his treatment of the poor)."