He said: Abul Hasan ALI b. Bilal al-Mahlabi reported to me from ALI b. Abdillah b. Asad al-Isfehani, who reported from Ibrahim b. Muhammad al-Thaqafi, who reported from al-Qannad, who reported from ALI b. Hashim, from his father, from Saeed b. al- Musayyib who said:
I heard AMIRUL MO’MINEEN ALI BIN ABI TALIB (ASWS), say: "There is no verse between the two covers of the Qur'an, except that I know for whom it was revealed and when it was revealed, and whether on a plain, levelled land or upon a mountain. Surely, here in my breast is abundant knowledge! So, put your questions to me before you do not find me among yourselves, for when you have lost me, you will not find anyone uttering the words I utter."
(Ref :Al-Amali Shaikh Mufeed: The Nineteenth Assembly Hadees no. 3)