SHAFAQNA – We have studied that the words of the infallible is the (Divine) proof whether the infallible is Imam or Prophet or none of them. The basis is the authority and the infallibility. If a person is totally immune from the influence of illusion, hallucination and mischief and if there is no way that such a person will be forgetful and if whatever such a person does, is for the satisfaction of God, then this person becomes an infallible and his/her words become the proof. In some of narrations from Imam Ali (AS), he quoted from Lady Fatima Zahra (AS) and in other times, other Imams Quoted from him .
 Alkafi, Vol. 1, Page 240 and Vol. 8, Page 57.
Source: Isra Website, Part of speech by the Grand Ayatollah Javadi Amoli in Qom on 10 April 2013.