´Narrated 'Ali:` that concerning Al-'Abbas, the Prophet (ﷺ) said to 'Umar: "Indeed, the uncle of a man is the Sinw of his father." And 'Umar had spoken to him concerning his charity.
Shaykh Dr. Abdur Rahman Freywai
Explanation: 1: It is recorded in Sahih Bukhari and Sahih Muslim that the Messenger of Allah (sallallahu alayhi wa sallam) sent Umar (radi Allahu anhu) to collect the wealth of zakat, but some people refused to give it. Among them was your (sallallahu alayhi wa sallam) uncle, Abbas (radi Allahu anhu). Regarding him, the Prophet (sallallahu alayhi wa sallam) said to Umar: (وَأَمَّاالْعَبَّاسُفَهِيَعَلَيَّوَمِثْلَهَامَعَهَا), meaning: As for my uncle Abbas, his due is upon me, and the like of it in addition. Along with this, the Prophet (sallallahu alayhi wa sallam) also said what is mentioned in the hadith.
Note: (Based on supporting evidence, the hadith is authentic. See: Hadith number: (3761) and al-Sahihah: 806)
Source: Sunan al-Tirmidhi – Majlis ‘Ilmi Dar al-Da‘wah, New Delhi Edition, Page: 3760