Sahih Bukhari Volume 009, Book 090, Hadith Number 341.

Narrated By Sa'd bin Ubaid : (The Maula of 'Abdur-Rahman bin Azhar) Allah's Apostle said, "None of you should long for death, for if he is a good man, he may increase his good deeds, and if he is an evil-doer, he may stop the evil deeds and repent."