Sahih Muslim Book 45, Hadith 66
Never a believer is stricken with discomfort, hardship or illness, grief or even with mental worry that his sins are not expiated for him.
I heard Allah's Messenger (ﷺ) as saying: There is nothing (in the form of trouble) that comes to a believer even if it is the pricking of a thorn that there is decreed for him by Allah good or his sins are obliterated.
"Whoever does evil will be requited for it", and when this was conveyed to the Muslims they were greatly perturbed. Thereupon Allah's Messenger (ﷺ) said: Be moderate and stand firm in trouble that falls to the lot of a Muslim (as that) is an expiation for him; even stumbling on the path or the pricking of a thorn (are an expiation for him). Muslim said that 'Umar b. Abd al-Rahman Muhaisin was from amongst the people of Mecca.