Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) narrates: Sayyiduna Abu Sufyan bin Harb himself told me this incident. He says, during the period when there was a peace treaty between us and the Prophet Muhammad (peace be upon him), I went to Syria. While I was in Syria, a letter from the Prophet Muhammad (peace be upon him) arrived for Heraclius (the ruler there). Dihyah Kalbi brought that letter. He handed the letter over to the governor of Busra. The governor of Busra sent the letter to Heraclius. Heraclius inquired: Is there anyone here from the people of this man who claims to be a prophet? The people replied: Yes. (Abu Sufyan says:) So I was summoned along with some individuals from the Quraysh. When we came to Heraclius, he seated us before him. He asked: Who among you is the closest in lineage to this man who claims to be a prophet? Sayyiduna Abu Sufyan says: I replied, I am. So he seated me in front of him and my companions behind me. Then he called his interpreter and said: Tell them that I am going to ask this man about the one who claims to be a prophet. If he lies to me, you all should declare him a liar. Abu Sufyan says: By Allah! If I had not feared that any of my statements could be refuted, I would have lied there. Then Caesar said to his interpreter: Ask this man about the lineage of this person among you. Abu Sufyan says: I replied, He is considered of noble lineage among us. Caesar asked: Was there any king among his ancestors? I replied: No. He asked: Before he claimed this, did you ever accuse him of lying? I replied: No. He asked: Who are his followers? Are they the noble or the weak? I replied: Rather, the weak. He asked: Is their number increasing or decreasing? I said: They are increasing. He asked: Has anyone among them, after accepting his religion, become displeased and left his religion? Abu Sufyan says: I replied: No. Caesar asked: Have you fought any battles with him? I replied: Yes. He asked: What was the outcome of your battles with him? I said: The battle between us and them has been equal. They have suffered losses from our side, and we have suffered losses from their side. Caesar asked: Has he ever broken a treaty? I replied: No. There is a treaty between us and them for a fixed period. We do not know what they will do in the future regarding this. (Sayyiduna Abu Sufyan says:) Only this statement I was able to add as a falsehood. Caesar asked: Has anyone before him ever claimed such a thing? I replied: No.

Then Caesar said to his interpreter: Tell him, I asked you about his lineage among you, and you stated that he is considered of noble lineage among you. Such are the messengers; they are sent among the noble of their people. I asked you whether there was any king among his ancestors, and you replied: No. So I thought, if there had been a king among his ancestors, I could have said that this man is seeking the kingdom of his ancestors. Then I asked you about his followers: Are they the weak or the noble? You said: They are the weak. Such are the followers of the messengers. I asked you, before he claimed this, did you ever accuse him of lying? You replied: No. From this, I realized that a person who does not lie to people, how could he lie about Allah? Then I asked you, has anyone, after accepting his religion, become displeased and left his religion? You replied: No. Faith is like this; when its delight enters the heart (or its delight settles in the heart). I asked you, is their number increasing or decreasing? You replied: Increasing. Faith is like this until it is complete. I asked you, have you fought any battles with him? You replied: The outcome of the battle between you and them has been equal. You suffered losses from their side, and they suffered losses from your side. Messengers are tested in this way, but in the end, the outcome is in their favor. I asked you, has he ever broken a treaty? You replied: No. Such are the prophets; they do not break treaties. I asked you, has anyone before him ever claimed such a thing? You replied: No. I thought, if someone before him had claimed this, I could have said that this man is following someone else's statement. Then Caesar asked: What does he command you? I replied: He commands us to pray, to give zakat, to maintain ties of kinship, and to be chaste.

Caesar said: If what you have said about him is true, then he is indeed a prophet. I knew that he was about to appear, but I did not think that he would appear among you. If I knew that I could reach him, I would love to meet him, and if I were with him, I would wash his feet, because soon his kingdom will reach under these feet of mine. Sayyiduna Abu Sufyan (may Allah be pleased with him) narrates: Then he called for the letter of the Prophet Muhammad (peace be upon him) and read it. It was written in it:

"In the name of Allah, the Most Gracious, the Most Merciful. From Allah's Messenger Muhammad (peace be upon him) to Heraclius, the ruler of Rome. Peace be upon him who follows guidance. To proceed: I invite you to Islam. Accept Islam, you will be safe. Accept Islam, Allah will grant you a double reward. But if you turn away, then the sin of the Arisiyun will be upon you. (The command of Allah is:) 'O People of the Book! Come to a word that is just between us and you, that we worship none but Allah.' Up to the verse: 'Bear witness that we are Muslims.'"

When Caesar finished reading the letter, voices were raised around him and there was an uproar. By his order, we were expelled from there. When we came out, I said to my companions: The matter of Ibn Abu Kabsha (i.e., the Prophet Muhammad, peace be upon him) has become so great that even the ruler of Banu Asfar fears him.

Sayyiduna Abu Sufyan narrates: After that, I became certain regarding the matter of the Prophet Muhammad (peace be upon him) that Allah would grant him dominance, until Allah blessed me with the wealth of Islam.