The Islam of al-Abbas (may Allah be pleased with him) and the differing reports on when he accepted Islam

It is narrated from Sayyiduna Abu Rafi' (may Allah be pleased with him), the freed slave of the Messenger of Allah (peace and blessings be upon him): I was a slave of Sayyiduna al-Abbas bin Abd al-Muttalib (may Allah be pleased with him). I had accepted Islam, Umm al-Fadl (may Allah be pleased with her) had also accepted Islam, and Sayyiduna al-Abbas (may Allah be pleased with him) had also become Muslim, but he used to conceal his Islam out of fear of his people. Abu Lahab had not taken part in the Battle of Badr; rather he had sent in his place al-As bin Hisham, who owed him a debt. He had said to him: "Go to this fight in my place and I will forgive you your debt," and so he did. When the news of the defeat at Badr arrived and Allah humiliated and disgraced Abu Lahab, I was at that time a weak man, and I used to carve cups in a chamber. By Allah, I was sitting in the chamber carving my cups, and Umm al-Fadl was with me, when that wicked Abu Lahab came dragging his feet and sat down by the tent-rope of the chamber, behind my back. The people began saying: This is Abu Sufyan bin al-Harith coming. Abu Lahab said: "O my nephew, come to me." So Abu Sufyan came and sat by him, and the people also came and stood around the two of them. Abu Lahab asked: "O my nephew, how did things go for the people in the battle?" He said: "Nothing at all. By Allah, no sooner did we meet them than we handed them our shoulders; they killed us however they wished and took us captive however they wished. And by Allah, I do not blame the people." Abu Lahab asked: "Why?" He said: "Because I saw men clothed in white on piebald horses. By Allah, they spared nothing, and nothing could stand before them." Abu Rafi' says: I lifted the curtain of the chamber and said: "By Allah, those were the angels!" At that Abu Lahab raised his hand and slapped me in the face. I grappled with him, but he lifted me up, threw me to the ground and sat on top of me. Seeing this, Umm al-Fadl got up, took one of the posts of the chamber and struck him on the head so hard that it left a very deep and ugly wound on his head, and she said: "O enemy of Allah, did you think him weak because his master is not here with him?" So he got up humiliated. By Allah, after that he lived only seven nights, until Allah afflicted him with the disease of 'adasah' (a plague-like pustule), which killed him. His sons left him like that for two or three nights and did not bury him, until his corpse began to rot. A man of Quraysh said to his sons: "Are you not ashamed? Your father is rotting in the house." They said: "We fear the contagion of this sore." And Quraysh feared adasah just as plague is feared. The man said: "Come, I am with you." Abu Rafi' says: By Allah, they did not wash him; rather they threw water on him from a distance, then they carried him and dumped him beside a wall in the upper part of Makkah and threw stones over him.

It is narrated from Urwah bin al-Zubayr that Sayyiduna al-Abbas bin Abd al-Muttalib (may Allah be pleased with him) had accepted Islam and remained in Makkah in charge of his siqayah (the service of giving water to the pilgrims), and he had not (at that time) emigrated.

It is narrated from Sayyiduna Jabir (may Allah be pleased with him): My maternal uncle Jadd bin Qays took me (to Makkah) with the seventy riders of the Ansar who came as a delegation to the Prophet (peace and blessings be upon him). At that time I was so young that I did not even have the strength to throw a stone. The Messenger of Allah (peace and blessings be upon him) came out to us, and with him was his paternal uncle Sayyiduna al-Abbas (may Allah be pleased with him). He (peace and blessings be upon him) said: "O uncle, take the pledge for me from these maternal uncles of yours (the Ansar)." The Ansar said: O Muhammad (peace and blessings be upon him), lay down whatever conditions you wish for your Lord and for yourself. He (peace and blessings be upon him) said: "For myself I take this covenant from you: that you will protect me just as you protect your wealth and your lives." They asked: If we do that, what reward will we get? He (peace and blessings be upon him) said: "Paradise."
This hadith has a sahih (authentic) chain of transmission, but the two Shaykhs did not record it. And there is no report more authentic than this hadith about Sayyiduna al-Abbas (may Allah be pleased with him) being among the early Muslims.