When does the time for Fajr prayer begin, and is it true that the difference between the prayer time in the calendar and the time of sunrise reaches an hour and a half in Egypt?

The time for Fajr prayer extends from the emergence of dawn (Fajr) until sunrise. Whoever prays within this time has performed it within its due time. As for one who intentionally delays it until after sunrise, they have committed a grave sin, and some scholars hold that it is as if they have abandoned the prayer. The duration between the emergence of dawn and sunrise is approximately an hour and a half, according to the calendar, and the calendar is the means by which prayer times are known. One must observe the five daily prayers at their prescribed times, for they are the pillar of Islam, as Allah the Almighty says: (And those who are constant in their prayers) and His saying: (Guard strictly the prayers, especially the middle prayer). The middle prayer is the Asr prayer.