The noble author indicates that it is obligatory according to the sacred law [sharī’ah] upon the legally responsible [mukallaf] person to have knowledge [ma’rifah] of what is necessary [wājib] regarding his Creator (Most High).
Imām Bājūri said: The letter fā in [fa kullu] is referred as [fa al-fasīha] and it clarifies [fasahat] something that is hidden. That which is hidden, meaning that which the fa al-fasiha represents is “if you want an explanation of the foundations of the religion, then I say to you [idha aradta bayāna ‘ilmi usūl al-dīn fa aqūlu laka]” and upon every legally responsible [fa kullu man kullafa…]. Meaning that it is necessary for every legally responsible individual from amongst human beings and jinn, male and female, layman [‘awām] and slave [‘abīd] including the tribes of gog and magog [ya’jūj wa ma’jūj]. This excludes the angels [dūna al-malā’ikah] even though they are said to be regally responsible [mukallaf]. This is because their responsibility is related to other than investigating and knowing Allāh (Most High) as this comes naturally to them [fa’innahā jibillatu lahum]. There is none amongst them who are ignorant regarding the divine attributes of Allāh (Most High) as is the case with human beings and jinn. This is why Allāh (Most High) firstly says, “Allāh bears witness to His Oneness and so do His angels”, followed by “and those of knowledge”. So He (Most High) did not generalize the matter with human beings like He (Most High) did with the angels. As for responsibility [taklīf]: it is the necessity to do something which carries some burden [ilzāmu mā fīhi kulfah]. It is also said that it means to seek to do something which carries some burden [talaba mā fīhi kulfah]. The first definition is the stronger one [rājih].
 Qurān 3:18