Tafsir Al-Jalalayn: Ash-Shura, Ayah 30

And whatever affliction whatever misfortune or hardship may befall you — this is an address to the believers — is on account of what your own hands have earned that is to say for the sins that you have committed — the use of ‘hands’ to express this is because most actions are effected by them. And He pardons much of these sins and does not requite them for God’s kindness is greater than that He should for example double the requital in the Hereafter; as for those who do not commit grave sins then what befalls them in this world of hardship raises their degree in the reward of the Hereafter.