Maliks Muwatta Book 50, Hadith Number 8.
Section : The Reward of the Invalid.
Yahya related to me from Malik from Yahya ibn Said that death came to a man in the time of the Messenger of Allah, may Allah bless him and grant him peace. A man said, “He was fortunate,” as he had died without being tried by illness. The Messenger of Allah, may Allah bless him and grant him peace, said, “Alas for you, what will let you know that if Allah had tried him with illness, He would have wiped out his wrong actions.”