'One of the firm decisions of Allah in the Wise Reminder (the Qur'an) ... is that it will be of no avail to man to strive with his soul and to act sincerely, if upon leaving this world to meet his Lord he is still guilty of any of the following sins for which he has not repented: that he associated anything else with Allah in his obligatory worship, or appeased his own anger by killing someone, or exposed acts committed by others, or sought fulfilment of his needs from people by introducing an innovation in his religion, or was two-faced in his encounters with people, or mingled among them deceitfully.'