What is the meaning of the saying mentioned above: “to comply with its rules,” “to comply with what is obligatory upon them of the religious rules.”?
It means to adhere to the rules that the Religion of Islam ordered the individual to follow by fulfilling all the obligations due upon them and refraining from all the sins. One learns about the obligations and sins by acquiring the Personal Obligatory Knowledge. A pious person is the one who performs the obligations and avoids the prohibitions. The one who dies on that state shall be admitted to Paradise without torture.