Musnad Ahmad 32:1768

'Affan narrated to us, Hammad ibn Salamah narrated to us, Abu Rabi'ah narrated to us, from Anas, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "If Allah tests the Muslim servant with a trial in his body, He says to the angel: 'Write for him his righteous deeds that he used to perform.' Then, if He heals him, He washes him and purifies him; and if He takes his soul, He forgives him and has mercy upon him."