Musnad Ahmad 8:171

Ali ibn Abdullah narrated to us, Muhammad ibn Talhah al-Taymi, from the people of Medina, narrated to me, Abu Suhail Nafi ibn Malik narrated to me, from Sa'id ibn al-Musayyib, from Sa'd ibn Abi Waqqas, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said to al-Abbas: "This is al-Abbas ibn Abd al-Muttalib, the most generous of the Quraysh in hand and the most upholding of them to kinship ties."