“Once a man came to Amir al-Mu’minin, Ali ibn abu Talib (a.s.) and asked him, ‘What is the least of that with which a servant (of Allah) becomes a believer, or an unbeliever or a straying person?’ I heard the Imam say, ‘You asked the question, now try to understand the answer. The least of that with which one may be considered a believer is that Allah, the Most Blessed, the Most High, makes him know His Ownself, then he professes to obey Him. He (Allah) makes him know His Holy Prophet, then he professes to obey him and He makes him know His Imam, His Authority on His earth and His witness over His creatures, then he professes to obey him. ’ “I then asked, ‘O Amir al-Mu’minin, does this hold true even if one is ignorant of all other things besides what you just mentioned?’ The Imam said, ‘Yes, if he when commanded obeys and when prohibited upholds it. The least of that with which a servant (of Allah) becomes an unbeliever is that when upon a mere guess one says that this is what Allah has commanded and this is what Allah has prohibited. Then he assigns it to be his religion upon which he bases his system of guardianship (religious authority). He guesses that he obeys the one who has commanded him to do it and, in fact, he worships Satan only.’ “The least of that with which a servant (of Allah) is considered straying is when he does not know the Authority of Allah, the Most Blessed, the Most High, His witness over His servants. The Authority about whom Allah, the Most Majestic, the Most Holy, has commanded His servants to obey and has made it obligatory to love him as one’s Divine Guardian.’ I then said, ‘O Amir al-Mu’minin, describe them (the people who possess Divine Authority) for me.’ The Imam said, ‘They are those whom Allah, the Most Majestic, the Most Holy, has mentioned along with His Ownself and His Holy Prophet saying, ‘Believers, obey Allah, His Messenger, and your leaders (people who possess Divine Authority). . . .’ (4:59) I said, ‘O Amir al- Mu’minin, May Allah keep my soul in service for your cause, explain it to me.’ The Imam said, ‘They (people who possess Divine Authority) are those about whom the Messenger of Allah in his last sermon on the day that Allah, the Most Majestic, the Most Holy, took him (from this world) said, ‘I leave among you behind me two matters. If you will hold firmly to these two you will never stray: the book of Allah and my descendents, my family. The Most Subtle and Most Expert, (Allah) has informed me that these two will never separate from each other until they will arrive before me at the pond in paradise like this - he joined his index finger and thumb - not like this - he joined his middle finger and thumb so that one may proceed before the other. You must hold firmly to these two, you will not slip, or stray and do not go before them; you will stray.’”