Abu Hurairah (May Allah be pleased with him) reported:
Messenger of Allah (ﷺ) said, "Be prompt in doing good deeds (before you are overtaken) by turbulence which would be like a part of the dark night. A man would be a believer in the morning and turn to disbelief in the evening, or he would be a believer in the evening and turn disbeliever in the morning, and would sell his Faith for worldly goods."[Muslim].
Arabic/English book reference: Book 1, Hadith 87