It was Gabriel that came down revealing to him...

It was Gabriel that came down revealing to him, (O you who are wrapped up, arise and warn, and your Lord do magnify, and your garments do purify, and uncleanness do shun, nor expect, in giving, any increase (for yourself), and for the sake of your Lord, be patient.)[1] Allah ordered him to rise and invite people to monotheism on which all powers of good and peace would be based and to warn them against the severe torment of Allah that He would afflict the unjust and the unbelievers with.

Khadijah asked him to go back to his bed, but he replied, “O Khadijah, the time of sleep and rest has gone. Gabriel has ordered me to warn people and to invite them towards Allah and towards His worship. Whom shall I invite and who will respond to me?” Khadijah and Ali’s faith At once, Khadijah believed and embraced Islam, and then Imam Ali (a.s.) embraced Islam. They were the first ones who became Muslims.

[2] Imam Ali (a.s.) talked about his and Khadijah’s precedence in embracing Islam by saying, “…and no house, then, gathered in [1] Qur'an, 74:1-7. [2] Sahih of at-Termithi, vol. 2 p. 301, at-Tabaqat al-Kubra by ibn Sa’d, vol. 3 p. 12, Usd al-Ghabah, vol. 4 p. 17, Kanzol Ummal, vol. 6 p. 400, Tareekh at-Tabari, vol. 2 p. 55, Tareekh Baghdad, vol. 2 p. 18, and others.

Islam except the messenger of Allah, Khadijah, and me the third of them.” [1] When becoming a Muslim, Imam Ali (a.s.) was seven years old, and it was said nine years. [2] The Prophet’s prayer in the Kaaba On the second day of the revelation and prophethood, the Prophet (a.s.) went to the Kaaba and offered the prayer in it. [3] Khadijah and Imam Ali (a.s.) offered the prayer behind him, and this was the first prayer in Islam offered in the Holy Kaaba.

This prayer was a matter of wonder and astonishment. Afif al-Kindi narrated, “Once in the pre-Islamic era, I came to Mecca intending to buy from its clothes and perfumes to my family. I went to al-Abbas bin Abdul Muttalib who was a merchant. While I was sitting with him looking at the Kaaba and the sun was high in the sky, a young man came, looked at the sky, and stood up towards the Kaaba.

After no long, a young boy came and stood on his (the young man) right, and then a woman came and stood on his left. The young man bowed down, and the young boy and the woman bowed down like him. Then, the young man prostrated and the young boy and the woman did the same. I said astonishedly, ‘O Abbas, it is a wonder!’ Al-Abbas said, ‘Yes, it is a wonder.