Imam Mahdi (AS) has said that if anybody were to narrate his sayings, he should compare the narrations with the Quran; if it is in conformity with the Quran, it is from him (the Imam). But if it is not conforming to the word of Allah, it is not from him (Imam Mahdi (AS)); may be the narrator could not comprehend his (the Imam's) sayings.
(Insaaf Nama - Matan Sharif N.11)