How did Khadija bint Khuwylid (ra) embrace Islam?

In a Nutshell: Khadija (ra) was the first person to believe the Messenger (saw). She did not receive dawa from him, rather he (saw) narrated his experience of the first revelation in the cave to her. She consulted her Christian cousin Waraqa ibn Naufal who told them "This revelation is similar to what Moses received." Khadija (ra) converted before the Messenger started calling society to reorient to Islam. The Story of Khadija's Conversion When the Messenger (saw) first received revelation in cave Hira, he was fearful and confused. He returned home to his wife Khadija (ra) telling her to "Cover me!" out of fear. Later when he was able to speak, he told her about what he had experienced in the cave. He was confused and did not know what he was supposed to do, what he saw. The words 'Read in the name of your Lord,' did not tell him of his mission. Khadija (ra) suggested seeking the advice of a specialist of scriptures, her cousin Waraqa ibn Naufal, who was a Christian scholar. Waraqa listened to the Messenger (saw) and acknowledged this was revelation via Jibreel, and told them what he was hearing was similar to the revelation Moses received. A'isha (ra) narrated the events surrounding the first occasion of revelation: اقْرَأْ‏.‏ فَقُلْتُ مَا أَنَا بِقَارِئٍ‏.‏ فَأَخَذَنِي فَغَطَّنِي الثَّالِثَةَ، ثُمَّ أَرْسَلَنِي فَقَالَ ‏{‏اقْرَأْ بِاسْمِ رَبِّكَ الَّذِي خَلَقَ * خَلَقَ الإِنْسَانَ مِنْ عَلَقٍ * اقْرَأْ وَرَبُّكَ الأَكْرَمُ‏}‏ ‏‏ فَرَجَعَ بِهَا رَسُولُ اللَّهِ صلى الله عليه وسلم يَرْجُفُ فُؤَادُهُ، فَدَخَلَ عَلَى خَدِيجَةَ بِنْتِ خُوَيْلِدٍ رضى الله عنها فَقَالَ ‏"‏ زَمِّلُونِي زَمِّلُونِي ‏"‏‏.‏ فَزَمَّلُوهُ حَتَّى ذَهَبَ عَنْهُ الرَّوْعُ، فَقَالَ لِخَدِيجَةَ وَأَخْبَرَهَا الْخَبَرَ ‏"‏ لَقَدْ خَشِيتُ عَلَى نَفْسِي ‏"‏‏.‏ فَقَالَتْ خَدِيجَةُ كَلاَّ وَاللَّهِ مَا يُخْزِيكَ اللَّهُ أَبَدًا، إِنَّكَ لَتَصِلُ الرَّحِمَ، وَتَحْمِلُ الْكَلَّ، وَتَكْسِبُ الْمَعْدُومَ، وَتَقْرِي الضَّيْفَ، وَتُعِينُ عَلَى نَوَائِبِ الْحَقِّ‏.‏ فَانْطَلَقَتْ بِهِ خَدِيجَةُ حَتَّى أَتَتْ بِهِ وَرَقَةَ بْنَ نَوْفَلِ بْنِ أَسَدِ بْنِ عَبْدِ الْعُزَّى ابْنَ عَمِّ خَدِيجَةَ ـ وَكَانَ امْرَأً تَنَصَّرَ فِي الْجَاهِلِيَّةِ، وَكَانَ يَكْتُبُ الْكِتَابَ الْعِبْرَانِيَّ، فَيَكْتُبُ مِنَ الإِنْجِيلِ بِالْعِبْرَانِيَّةِ مَا شَاءَ اللَّهُ أَنْ يَكْتُبَ، وَكَانَ شَيْخًا كَبِيرًا قَدْ عَمِيَ ـ فَقَالَتْ لَهُ خَدِيجَةُ يَا ابْنَ عَمِّ اسْمَعْ مِنَ ابْنِ أَخِيكَ‏.‏ فَقَالَ لَهُ وَرَقَةُ يَا ابْنَ أَخِي مَاذَا تَرَى فَأَخْبَرَهُ رَسُولُ اللَّهِ صلى الله عليه وسلم خَبَرَ مَا رَأَى‏.‏ فَقَالَ لَهُ وَرَقَةُ هَذَا النَّامُوسُ الَّذِي نَزَّلَ اللَّهُ عَلَى مُوسَى صلى الله عليه وسلم يَا لَيْتَنِي فِيهَا جَذَعًا، لَيْتَنِي أَكُونُ حَيًّا إِذْ يُخْرِجُكَ قَوْمُكَ‏.‏ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ أَوَمُخْرِجِيَّ هُمْ ‏"‏‏.‏ قَالَ نَعَمْ، لَمْ يَأْتِ رَجُلٌ قَطُّ بِمِثْلِ مَا جِئْتَ بِهِ إِلاَّ عُودِيَ، وَإِنْ يُدْرِكْنِي يَوْمُكَ أَنْصُرْكَ نَصْرًا مُؤَزَّرًا‏‏.‏) "He then released me and again asked me to read but again I replied, 'I do not know how to read (or what shall I read)?' Thereupon he caught me for the third time and pressed me, and then released me and said, 'Read in the name of your Lord, who has created (all that exists), created man from a clot. Read! And your Lord is the Most Generous." (Qur'an 96:1-3) Then Allah's Messenger (saw) returned with the inspiration and with his heart beating severely. Then he went to Khadija bint Khuwailid and said, "Cover me! Cover me!" They covered him till his fear was over and after that, he told her everything that had happened and said, "I fear that something may happen to me." Khadija replied, "Never! By Allah, Allah will never disgrace you. You keep good relations with your kith and kin, help the poor and the destitute, serve your guests generously and assist the deserving calamity-afflicted ones." Khadija then accompanied him to her cousin Waraqa bin Naufal bin Asad bin Abdul Uzza, who, during the pre-Islamic Period became a Christian and used to write the writing with Hebrew letters. He would write from the Gospel in Hebrew as much as Allah wished him to write. He was an old man and had lost his eyesight. Khadija said to Waraqa, "Listen to the story of your nephew, O my cousin!" Waraqa asked, "O my nephew! What have you seen?" Allah's Messenger (saw) described whatever he had seen. Waraqa said, "This is the same one who keeps the secrets (angel Gabriel) whom Allah had sent to Moses. I wish I were young and could live up to the time when your people would turn you out." Allah's Messenger (saw) asked, "Will they drive me out?" Waraqa replied in the affirmative and said, "Anyone (man) who came with something similar to what you have brought was treated with hostility, and if I should remain alive till the day when you will be turned out then I would support you strongly." (Sahih al-Bukhari 3) Bayhaqi narrates: Later when Abu Bakr (ra) came and at that time Rasulullah (saw) was absent from the house. Then she told Abu Bakr (ra) about the condition of the Messenger (saw). And she said, "Take Muhammad to Waraqa." When the Messenger (saw) came home, Abu Bakr (ra) took his hand and said, "Come with me to Waraqa." The Messenger (saw) said to Abu Bakr, "Who told you these things?" Abu Bakr (ra) said, "Khadija did." The Messenger (saw) went to Waraqa with Abu Bakr (ra) and narrated all the details, "when I am stay alone from behind, O Muhammad, O Muhammad! I heard a voice. Hearing this, I came back from there quickly." Waraqa said, "When you hear this voice again, do not run away, but listen to what it says and then come to me." So when the Messenger (saw) was later alone, someone called him and said, "O Muhammad! Read 'Bismillahi Rahmani Rahim. Alhamdulillahi Rabbil Alamin...' Hearing this, the Messenger (saw) came to Waraqa and told him everything. Waraqa said to the Messenger (saw), "Take the good news, take the good news. I bear witness that you are the one whose good news Jesus (as) gave. And this angel (Gabriel) came to you that he would come to Moses (as). (Know that) you are a Messenger." (Ibn Kathir, as-Sirah al-Nabawiyyah, p. 289) There is no narration that details how Khadija (ra) embraced Islam afterwards. However, it seems she accepted Waraqa's observations especially as she knew her husband did not lie. Furthermore, the Messenger (saw) could hardly have asked her to accept Islam because, at that time, he had not been asked to convey anything. He did not even know the purpose of revelation nor its purpose. Allah commanded the Messenger (saw) to deliver the message with Sura Muddaththar which was revealed a short while later: يَا أَيُّهَا الْمُدَّثِّرُ، قُمْ فَأَنذِرْ، وَرَبَّكَ فَكَبِّرْ، وَثِيَابَكَ فَطَهِّرْ "O you who covers himself (with a garment), arise and warn, and glorify your Lord, and purify your clothing." (Qur'an 74:1-4) وَأَنذِرْ عَشِيرَتَكَ الْأَقْرَبِينَ، وَاخْفِضْ جَنَاحَكَ لِمَنِ اتَّبَعَكَ مِنَ الْمُؤْمِنِينَ "And warn, (O Muhammad), your closest kindred. And lower your wing to those who follow you of the believers." (Qur'an 26:214-215) These verses were certainly revealed after Khadijah and Ali (ra) converted. The first verse taught him of purification, followed by the teaching of ablution (wudu') and the prayer by Jibreel (as), soon after which the Messenger (saw) taught them to Khadija. (Ibn Hisham, al-Sirah al-Nabawiyyah, Vol. 1, p. 161) The second verse supposes there were already believers and Khadija (ra) was the first Muslim ever. In some narrations in the books of sirah, Khadija (ra) predicted the messengerhood and hoped it would come true. It was narrated she said: ْفَقَالت: يَا أَبا القَاسِم أيْنَّ كنتَ؟ فواللهِ لقَدَ بَعَثْتُ رُسُلِي في طَلَبِكَ حَتَى بَلَغُوا أَعْلَى مَكَةَ ورَجَعُوا. ثُمَ حَدَثْتُهَا بِالذي رَأَيّتُ، فَقَاَلتْ: أَبْشِر يا ابنّ عَمِي واثْبُتْ فوالذي نَفْسُ خَدِيجَةَ بِيَدِهِ إنِي لأَرْجُو أن تكونَ نَبِيَّ هَذِهِ الأُمَة. "She (Khadija) then said (after the Messenger descended down of the mountain). 'O Abu al-Qasim where were you? By Allah sent people to search for you and they had reached the end of Mecca (and did not find you) so they returned back.' I (the Messenger) narrated what I saw. She replied. 'Glad tidings my cousin, steadfast, by Him in Whose Hands my life is, I hope you became the Messenger of this nation.'" (Ibn Hisham, Vol 1, p. 248, Halabi, as-Sirah al-Halabiyyah, Vol. 1, p. 342, Kala'i, al-Iktifa', Vol. 1, p. 165, Ya'muri, 'Uyun al-Athar, p. 104, Dhahabi, Siyar A'lam al-Nuba'a', Vol. 26, p. 104) So she was waiting for such message and predicted its truthfulness before the Messenger (saw) started calling anyone to Islam. The contemporary historian Ahmed Ghalush says: وَخَدِيجَة رضيّ اللهُ عنها أَوَلَ من دَخَلتْ فِي الإسْلَامِ، آمَنَتْ بالرِسَالةِ قَبْل أنْ يَطْلُبَ الرسولُ صلى الله عليه وسلم مِنْهَا أن تُؤْمِن؛ لأنها كانت تُبَشِرُ بالرِسَالةِ، وتَنْتَظِرُهَا "Khadijah (ra) was the first companion to embrace Islam. She believed in the Message before the Messenger (saw) would ask her to believe because she predicted and waited for it." (Ghalush, as-Seera al-Nabawiyyah, p. 446) Conclusion Khadija (ra) was the first to believe in him, being told of his experience in the cave and Waraqa telling them 'this revelation is similar to what Moses received.' Khadija (ra) converted before the Messenger (saw) started calling people to Allah. References Ibn Hisham, as-Sirah al-Nabawiyyah Ibn Kathir, as-Sirah al-Nabawiyyah Halabi, as-Sirah al-Halabiyyah Kala'i, al-Iktifa' Ya'muri, 'Uyun al-Athar Dhahabi, Siyar A'lam al-Nuba'a'