Professor Ansarian referred to the case of mercy which is different for the divine Prophets, the Ahlulbayt (peace be upon them) and the people. The divine prophets had no sins and they had no greediness in worshiping, I have no idea on what basis the case of mercy for them is, but the reason that all these mercies have been posed is that Allah Almighty knew that we will be sick due to our external and internal sins, he knew we might be stricken to greediness. Then, in the verse of 180 of Surah al-Amrān, it is said: I have granted that pious one lawful wealth, but he gets stingy about it and kept it for himself and has no tendency to share it with those who are in dire need of it. The holy Quran says about this issue: on the day of resurrection, all this wealth will change into a necklace of fire and will be wrapped around his neck and it will be never taken off his neck.
Professor Ansarian said: Allah Almighty knew that the believer will be stricken to internal and external diseases. One reason for the mercy case is that if you get polluted by sins, I am merciful, come back to me; come and cure yourself and avoid going to the hell.
source : erfan.ir
