Annemarie Schimmel believed that "The absolute obedience owed to the Prophet is meaningful only if Muhammad is free from any faults and could thus constitute an immaculate model for even the most insignificant part of life." Shia and some Sunni scholars believe that the prophets were given Ismah even before their assignment to the prophecy, and that it covered every aspect of their life including the emotional, behavioral, personal, social, intentional and unintentional. Representing Shi‘ites' point-of-view, Tabatabaei stated that Ismah took two forms with regard to revelation: firstly, that the prophets were necessarily free from sin in the reception of revelation, in its preservation, and in its propagation, due to the principle of ontological guidance, which stated that God, in His omniscience and omnipotence, did not err in guiding those whom He desired to guide; and, secondly, that Ismah implied protection from sin based on the prophets' will and knowledge. Tabatabaei also said that if the prophets' actions contradict their words, setting one example by their actions but preaching something else, this would obscure the truth, which would undermine the religious mission of the prophets, therefore, that the Ismah of the prophets in delivering the message of Allah depends upon their Ismah with regard to their inability to sin. Another argument from him was that all the prophets were guided by God, that everyone who is guided by God never sins, and that the prophets were therefore free from error.