Some points can be understood from mentioned traditions and many other similar ones:
1. Islam was completed during Prophet Muhammad’s (`a) lifetime and all required sciences, teachings, and rules were received through revelation.
2. The Messenger of Allah (s) attempted in publicizing and imparting the commandments in two ways; first, imparting them to the people and recommending they maintain and follow the commandments and second, saving all of the commandments in a secure place completely immune to forgetfulness and mistakes, that is Imam Ali’s (`a) luminous heart.
3. Prophet Muhammad (s) recommended Imam Ali (`a) to record and write the traditions and leave them for the following Imams (`a).
4. Therefore, some books were compiled by Imam Ali (`a), who used them after Prophet Muhammad’s (s) demise. After Imam Ali’s martyrdom the books were given to Imam Hassan (`a) and to other infallible Imams (`a) successively.
Reference to the Books
The mentioned books were with the infallible Imams (`a) and they attributed their knowledge to them. Each of the Imams (`a) transmitted religious sciences and commandments to his successor in two ways; verbal training and granting of books and permission to narrate from them. Each of the Imams attributed his traditions to the Prophet (s) through his fathers, as is seen in traditions.
Husham Ibn Salim, Hamad Ibn Uthman, and other people have narrated from Imam Sadiq (`a), “My tradition is the tradition of my father and his tradition is the tradition of my grandfather. The tradition of my grandfather is the tradition of Imam Hussayn (`a) and his tradition is the tradition of Imam Hassan (`a), whose tradition is the tradition of Amiral Mu’minin (`a). The tradition of Amiral Mu’minin (`a) is the tradition of Messenger of Allah (s) and his tradition is the speech of the Exalted Allah.” 
Jabir says, “I told Imam Baqir (`a), ‘When you recite a tradition for me, please mention its document.’ Imam Baqir (`a) said, ‘My father has narrated traditions from my grandfather and he from Gabriel and he from the Almighty Allah. Every tradition I recite for you has the same document. O Jabir! If you acquire a tradition from a truthful narrator, it will be better than the whole world for you.’” 
Hafs says, “I told Imam Sadiq (`a), ‘I have heard a tradition, which I am not sure is from you or your father.’ He stated, ‘What you hear from me you can narrate from my father and the Messenger of Allah (s).’”
With regard to above-mentioned discussion it can be said that a major source of knowledge of infallible Imams (`a) is the traditions compiled from Prophet Muhammad’s speech by Imam Ali (`a), which is transmitted to infallible Imams (`a). As a result, although the Imams (`a) were deprived of direct revelation, they benefited from revelation sciences indirectly. Each of the Imams (`a) narrated traditions with the most reliable documents –all whose narrators were infallible– from direct revelation. What an honor!
 Kafi, Vol 1, p. 53.
 Jami’ Ahadith Al-Shi’ah, Vol 1, p. 181.
 Ibid, p. 181.