Hadith:Salatul Fajr

The Prophet (peace and blessings of Allaah be upon him) said: “There are two dawns. With regard to the dawn which is like the tail of a wolf, this does not make it permissible to pray and haraam to eat. With regard to the dawn which appears horizontally in the sky, this makes it permissible to pray and forbidden to eat.”(Saheeh al-Jaami’)