Musnad Ahmad 32:1557

Hassan narrated to us, Hammad bin Salamah narrated to us, from Abu Rabi'ah, from Anas bin Malik, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "There is no servant whom Allah tests with an affliction in his body, except that Allah says to the angel: 'Record for him his righteous deeds that he used to perform.' If He heals him, He washes him and purifies him; and if He takes his soul, He forgives him and has mercy upon him."