Some people entered the morning with gratitude and some with ingratitude (to Allah). Those who entered with gratitude said: This is the blessing of Allah, and those who entered with ingratitude said: Such and such asterism was right. It was upon this that the verse was revealed: I swear by the setting of the stars to the end and make your provision that you should disbelieve it.
Sahih Muslim Book 1, Hadith 140