In his book of Tawilul Aayaatul Baahira, Sharafuddin Najafi has narrated from Salman Farsi that he said:
Once, I went to the house of Lady Fatima Zahra (s) and found Imam Hasan and Husain (a) playing while their mother was extremely pleased to watch them. After sometime Messenger of Allah (s) also arrived.
I said: O Messenger of Allah (s), please inform me about their excellence so that there may be increase in my love for them.
His Eminence said: Salman, when I was taken up to the heavens and Jibraeel took me on a tour of Paradise, I saw the localities and gardens of Paradise where I perceived a peculiar fragrance that had spread throughout the place and all the fragrances of Paradise seemed to be nothing as compared to this. I asked Jibraeel: What fragrance is this? It is dominating all the other fragrances of Paradise.
Jibraeel, the trustworthy angel, replied: It is the fragrance of an apple, which Almighty Allah created through the power of His hand three hundred thousand years ago and we don’t know for what exigency He created it? Jibraeel was explaining this to me when some angels arrived with that same apple and said:
“The Lord conveys His greetings to you and sends you this gift.”
I accepted the apple and placed it under the wing of Jibraeel and consumed it when Jibraeel brought me back to the Earth.
Almighty Allah collected its water in my loins and I established intimacy with Khadija binte Khuwailad and Fatima was conceived.
Almighty Allah revealed to me: I am creating in your house a Hourie in form of a human being.
Then He said: When she grows up, you marry the light to (another) light. That is: Marry Fatima to Ali (a). So I (God) have also married her to Ali in Paradise itself and deemed the Khums of the Earth as her dower.
Through Ali and Fatima would I create a purified progeny; these two: Hasan and Husain are the lamps of Paradise. Imams would be created from the progeny of Husain, who would be martyred and they would be abandoned without any helpers and friends. There is destruction for those who leave them without any helper and friend.
Tawilul Ayaat, Vol. 1, Pg. 236; Biharul Anwar, Vol. 36, Pg. 361.