Sahih Muslim | Book 32 | Hadith Number 6240

Narrated by 'Aisha
'Aisha said: No trouble comes to a believer even if it is the pricking of a thorn that it becomes (the means) whereby his sins are effaced or his sins are obliterated. Yazid says: He does not know which word 'Urwa said (whether he said Qussa or Kuffira).