Which mentions that the existence of Imam is essential in every period of the time and that no age ever remains without an Imam and that it is obligatory to obey him and that people do not get guidance but through the Imam and that it is necessary that the Imam must be clear of all sins and that he ought to be appointed by Allah. Also a brief description of the Divine texts (Nusoos) revealed regarding the Imams. So also some of their virtues. There are several Parts in this.