Abu Hurairah (May Allah be pleased with him) reported: Messenger of Allah (PBUH) 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].

Commentary: This Hadith tells that the Day of Resurrection will be preceded by a long chain of calamities. Because of the rush of these calamities, religion and Faith will loose their value in people. There will be a race for wealth, so much so that people would not hesitate to compromise their religion and Faith to acquire wealth. People will rapidly change their faces. This is what actually happening. In this situation true believers are exhorted to adhere strictly to Faith and perform noble deeds without delay.