Sayyidunā ʿAbū Hurayrah narrated: “The Messenger of Allāh ﷺ said: ‘Allāh Taʿālā inflicts hardships upon those whom He intends goodness for.”
Now, look! Sometimes, the question arises that there are also some close servants of Allāh regarding whom a person thinks that he does not have an accumulation of many sins. So then how was he afflicted with such a sickness? The answer to this is as follows. Primarily, he was afflicted from a different perspective. Allāh Taʿālā wished to raise his status.
It is mentioned in the Pure Ḥadīth that Allāh Taʿālā appoints a specific stage in Jannah for a servant which He will give him. However, that servant was unable of attaining that stage through his deeds. He does not possess any such action which will allow him to attain that stage. Thus, Allāh Taʿālā thereafter inflicts hardship upon him and grants him the tawfīq (Divine ability) to be patient. And when he exercises patience, he is bestowed that stage by Allāh Taʿālā. [See: Sunan ʾAbī Dāwūd #3090]
This is the system of Allāh. Thus, if a calamity befalls a person or he is afflicted with hardships, do not become distressed. One should not think that it is a punishment for a sin.
It is also not necessary that a hardship befalls a person due to sins. Sometimes, calamities occur for a greater good and not due to sins. Allāh Taʿālā wishes to bestow him with goodness. He wishes to bestow upon him tremendous bounties. Thus, he is also afflicted with hardships due to this reason.
[Dars Riyāḍuṣ Ṣāliḥīn Vol.1 Pg.298-300 by Hazrat Muftī Aḥmed Khānpūrī Ṣāḥib حفظه الله ونفعنا بعلومه وفيوضه وصحبته ]