Musnad Abu Ya'la al-Mawsili 129:123

Zuhayr narrated to us, Yazid bin Harun narrated to us, Humayd al-Tawil informed us, from Anas bin Malik: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Do not be amazed by anyone until you see how his life ends. For a worker may work for a period of his life, or a span of his time, doing good deeds—if he were to die upon them, he would enter Paradise—then he changes and performs evil deeds. And indeed, a servant may work for a period of his life doing evil deeds—if he were to die upon them, he would enter the Fire—then he changes and performs good deeds. And if Allah intends good for a servant, He employs him." They said: "O Messenger of Allah, how does He employ him?" He said: "He grants him success in performing a good deed, then He takes his soul upon it."