Among the incumbent attributes of the mūmin who aspires and strives hard to attain the station of iḥsān is to be sure of the Hereafter.
God –Glorified be He- says: “… and they are sure of the hereafter” [2:4]. So, instead of only believing in the hereafter, they are sure of it and are convinced with a definite certainty, untainted by any suspicion or doubt, that the abode of the Hereafter will follow this world, along with all that it contains, including the Resurrection and the Recompense, the Garden and the Fire, the Reckoning and the Balance. There is an indication here that one cannot be muḥsin, cannot guard himself against disbelief and be a truly mūmin, until he is really certain of the hereafter – a certainty that does not let him forget it even for a short time. A man believes in a matter, yet sometimes forgets some of its demands and then commits something contrary. But if he believes in, and is sure of, the day when he shall have to give account of all that he has done -big or small – he will not do anything against the divine law, will not commit any sin. God Almighty says: “. . . and do not follow desire, lest it should lead you astray from the path of God; (as for) those who go astray from the path of God, for them surely is a severe punishment because they forgot the Day of Reckoning.” [38:26]. Clearly it is because of forgetting the Day of Reckoning that man goes astray. It follows that if one remembers it and is sure of it, he will surely guard himself against evil, will become a devoted mūmin.
Furthermore, having certainty in the Hereafter is a cause of the attainment of both worldly and Otherworldly goals. According to Ḥātim al-Aṣamm -may God sanctify his innermost being-: “Adhere to the service of your Master, for then this world will come to you reluctantly, and the Hereafter willingly.”
It is therefore essential for the believer to be certain of the Hereafter, and to guard against anything that renders it null and void.