All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
It is among the Mercy of Allaah that when He punishes a person in this world for his sins, He will not punish him again in the Hereafter. The Prophet said: "No calamity befalls a Muslim except that Allaah expiates some of his previous sins for that, even if it were the prick he receives from a thorn." [Al-Bukhari and Muslim] Moreover, Mujaahid said: 'Any disease which a person is afflicted with in his body is due to a sin which he had committed, and any sin for which Allaah punishes the person for in this world, Allaah will not punish him for it again on the Day of Judgement, and the sins which Allaah has forgiven a person for, then Allaah is the Most Generous and would not hold people to account for sins which He has forgiven.'
Furthermore, Ibn Al-Qayyim commented on the saying of Allaah (which means): {And whatever of misfortune befalls you, it is because of what your hands have earned.}[Quran 42:30], saying: 'This is a glad tidings and a warning as Allaah informs us that the misfortunes of this world are a form of punishment for the sins one had committed, and Allaah is Most Merciful and thus would not double the punishment for a sin which He had already punished the person in this world for.'
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Allaah Knows best.