After the truce of Hudaybiyyah, the Prophet ﷺ was free to look beyond Arabia. He wrote letters to the rulers of the world, and the most famous of them went to Caesar, the Roman emperor. The emperor at that time was Heraclius, who reigned from 610 to 641. Muslim and non-Muslim historians alike remember him kindly. Heraclius was a scholar of Christianity. He tried, and failed, to reconcile its two great factions with a theology of his own. He was also a soldier. He had just won back everything the Persians had taken from Rome, as Surah al-Rum had foretold at a time when Rome seemed finished. Dihyah al-Kalbi carried the letter. He was to hand it to the governor of Busra, a town where the Quraysh went to trade, who would send it on. As it happened, Heraclius was in Jerusalem at the time, so the letter reached him at once. Abu Sufyan, who was still a pagan, was trading in Busra at the time. A crier summoned him and his companions to Jerusalem, and he found himself standing in the emperor's palace. Through an interpreter, Heraclius asked which of them was the closest relative of the man who claimed to be a prophet. Abu Sufyan was, so he was seated in front. His companions stood behind him, with orders to signal if he lied. He said afterwards that only the fear of being called a liar by his own people made him tell the truth. The emperor asked his questions one after another. He asked about the man's family, and Abu Sufyan said it was noble. He asked whether anyone among them had made this claim before him, and Abu Sufyan said no. He asked whether any of his ancestors had been a king, and again the answer was no. He asked whether the nobles followed him or the poor. Abu Sufyan said the poor. Heraclius asked whether his followers were growing or shrinking in number. Abu Sufyan said they were growing. He asked whether anyone who had entered his religion later left it in disgust. Abu Sufyan said no. He asked whether the man had ever been accused of lying before he began his mission. Again the answer was no. Heraclius asked whether he broke his word. Abu Sufyan said no. But he added that there was a truce between them now, and no one knew what he would do. Abu Sufyan admitted later that this was the one thing he could find to say against him. Heraclius asked whether they had fought him. Abu Sufyan said yes, and that sometimes he won and sometimes they did. Finally Heraclius asked what the man commanded. Abu Sufyan told him that he commanded them to worship God alone and abandon the gods of their fathers. He also told them to pray, to speak the truth, to be chaste, and to keep the ties of kinship. Then Heraclius explained why he had asked each question. Prophets, he said, come from noble families. If someone else had made the claim before, this man might be imitating him. If his fathers had been kings, he might be trying to win back his inheritance. A man who does not lie about money does not lie about God. The poor are always the first to follow the prophets. The truth always gains followers. Faith that has entered a heart and mixed with it is not thrown off. Prophets do not betray. And what this man commanded was what the prophets had always commanded. Heraclius said that if all this was true, the man would soon rule the very ground he was standing on. He said he had known from his scriptures that someone was coming, but he had not expected him to come from the Arabs. If he could reach him, he said, he would wash his feet. Then Heraclius called for the letter and had it read aloud. It began in the name of Allah. It was from Muhammad ﷺ, the servant of Allah and His Messenger ﷺ, to Heraclius, the great one of the Romans. It sent peace to whoever follows guidance. It told him to submit and be safe, and Allah would give him a double reward. If he turned away, he would carry the sins of the Arisiyin, a word whose meaning scholars have long debated. The letter closed with the verse of Ali Imran that calls the People of the Book to a word held in common, that none be worshipped but Allah. There was uproar in the court, and the Arabs were sent out. On the way out, Abu Sufyan spoke to his companions. The Quraysh mockingly called the Prophet ﷺ "Ibn Abi Kabsha", and Abu Sufyan said that the affair of Ibn Abi Kabsha had grown so great that even the king of the Romans feared him. He said later that it was there, in Caesar's palace, that Islam first entered his heart. That was three years before he actually embraced it. Sahih al-Bukhari keeps a second story about Heraclius, told separately from the first. One morning he woke up troubled by a dream in which he had seen the king of the circumcised appear. His courtiers told him that only the Jews were circumcised, and that he need only crack down on them. Then Dihyah arrived with the Prophet ﷺ's letter. When he was examined, he was found to be circumcised, and the emperor understood whom the dream was about. Heraclius wrote to a friend of his, most likely John IV. The friend wrote back that this was indeed the one. One theory, not stated in the sources, is that this same friend supplied the three tests that Heraclius later sent the Tanukhi to carry out. At last Heraclius gathered his senators and asked them what they thought of his following Muhammad ﷺ. They rushed for the doors, so he told them he had only been testing their faith. He died a Christian, in the confusion of a coup. He lived long enough to see Jerusalem taken by the people of his dream.
Safiyyah was a young girl in Madinah on the day the Prophet ﷺ arrived there. Her father was Huyayy ibn Akhtab, the chief of the Banu Nadir. She was his favourite child, and the favourite of her uncle Abu Yasir too. One day the two men came home from going to see the Prophet ﷺ. Safiyyah ran to greet them, but they walked straight past her with their shoulders slumped. Then she overheard them talking. Her uncle asked whether it was really him. Her father answered, "By the Lord of Moses, it is him." Her uncle asked what they would do now. Her father said they would oppose him for as long as he lived. Later Safiyyah was exiled along with her tribe. She settled in Khaybar and married there. In the fighting at Khaybar, the Banu Nadir threw themselves into the front line of its defence. More of them died than of Khaybar's own people, and her husband Kinana was among the dead. When the fighting ended, Safiyyah was a widow and a captive. When the captives were divided, she was given to Dihyah al-Kalbi. Some Companions told the Prophet ﷺ that the daughter of the chief of the Banu Nadir should be his, not left with Dihyah. So he paid Dihyah her price and took her. At first no one knew whether he had taken her as a servant or as a wife, so they watched. When it was time to leave Khaybar, he made his camel kneel. He knelt down himself and made his thigh into a step to help her mount. Out of respect, she placed her knee on it rather than her foot. Then he covered her with his cloak. At that the Companions understood, because that veil was only for his wives. Safiyyah herself did not yet know what it meant. When he went to her on the first night, she refused him, and he left her alone. When they were a night's journey from Madinah, she agreed. He asked Umm Sulaym to prepare her. Umm Sulaym hung two cloths between some trees, and the women did what they could with the little they had. They worried that they had no perfume or jewellery for her. But when they had finished, they smelt a scent finer than any they knew. When the Prophet ﷺ came in, he said the hard thing first. He said to her, "Your father Huyayy was the most open of the Jews in their animosity against me until Allah caused his death." This was a test of what was in her heart. She answered with a teaching of the Qur'an, that no soul bears the burden of another. Then he said to her, "You have a choice. If you accept Islam, I shall keep you for me; if you remain in your faith, then perhaps I will free you and you can return to your people." As she understood it, staying with him meant remaining a captive. She told him that she had been drawn to Islam even before he offered it, and had already believed in him. She said she had no people to go back to, since her father and her brother were gone. And she said that Allah and His Messenger ﷺ were dearer to her than her own family. So he freed her, made her freedom her dowry, and married her. He had noticed a bruise on her face and asked her about it. She explained that she had once told her husband about a dream. In it, the moon rose from Yathrib and fell into her lap. Her husband struck her and asked whether she expected the king of the Arabs to marry her. He had understood the dream correctly. Later she was asked why she had refused him on the first night. She said that they were still so close to Khaybar that she had feared the Jews would retaliate. The Prophet ﷺ loved her all the more for it. Abu Ayyub al-Ansari stood outside the tent all night with his sword drawn. He was afraid of what a woman whose family had died at Muslim hands might do. In the morning the Prophet ﷺ found him there. He laughed and prayed for him. The wedding feast was made of whatever anyone had. There were dates, a little clarified butter and barley, all mixed together. On the road home, the walls of Madinah came into sight. As was the custom in Madinah, the riders whipped their camels forward. The Prophet ﷺ's camel stumbled and threw both him and Safiyyah to the ground. Every Companion turned his face away. Only Abu Talha cried out to ask whether he was all right. The Prophet ﷺ replied, "I am okay; I am not hurt." He was on his feet at once and put his cloak over her. In Madinah the other wives came to look at her. Zaynab bint Jahsh said to Juwayriyya that this one would be trouble. Safiyyah belonged to neither of the groups among the wives, since she had no family of her own there. Perhaps that is why the Prophet ﷺ was so tender with her. Once Hafsa called her "the daughter of a Jew", and Safiyyah wept. The Prophet ﷺ asked her, "Why didn't you defend yourself?" She asked how. He said, "You should have said your father was a prophet (Harun), and your uncle was a prophet (Musa), and you are married to a prophet. What do they have over you?" On the Farewell Hajj, he stopped speaking to Zaynab because she refused Safiyyah a camel. In his last illness, Safiyyah said she wished she could take his fever on herself. The other wives said something unkind to her. He told them to rinse their mouths, and when they asked why, he said, "Because you have made fun of Safiyyah, and wallahi, she has spoken the truth." She died in 52 AH.
Heraclius, the Roman emperor, once woke up troubled. He said that he had seen a dream, and that his astrologers had read an evil omen. A leader had appeared among a new people who practiced circumcision, and this leader would challenge him. His senators told him there was nothing to worry about. The only people who circumcised, they said, were the Jews, so he could simply impose harsher rules on them. Before Heraclius could do this, Dihyah al-Kalbi arrived at his court with a letter from the Prophet ﷺ. Heraclius had him examined, and he was found to be circumcised. This made Heraclius deeply concerned, and he wrote to a friend about the matter, most likely John IV. Later, Heraclius gathered his senators and asked what they would think if he accepted the faith of Muhammad ﷺ. They reacted with fury and said he would never remain their emperor. So Heraclius told them he had only been testing their faith, and that he would never leave Christianity. He died upon his faith some years later, in the middle of a coup.