The Messenger of Allah (ﷺ) as saying: The summons (adhan) of Bilal should not restrain one of you from taking a meal shortly before dawn, for he utters adhan or calls (for prayer) so that the man at prayer may return, and the man asleep may get up. Dawn is not (the whiteness) which indicates thus (in perpendicular) - the narrator Musaddad said: Yahya joined his palms (indicating the spread of whiteness vertically - until it indicates thus - and Yahya spread out two ring-fingers of his (demonstrating the spread of whiteness horizontally)l
Hadith Commentary: The True Dawn
This noble hadith from Sunan Abi Dawud 2347 clarifies the distinction between the false dawn (al-fajr al-kadhib) and the true dawn (al-fajr al-sadiq) that marks the beginning of the daily fast.
Bilal's first adhan was given during the darkness of night to awaken those in voluntary night prayer (tahajjud) and allow those sleeping to prepare for Fajr. The true dawn appears as horizontal whiteness spreading across the horizon, not the vertical light that appears earlier.
Legal Rulings (Ahkam)
It is permissible to eat and drink until the true dawn appears, even after hearing Bilal's first call.
The fast begins only when the second adhan is called at the actual break of dawn, when the horizontal light spreads across the eastern horizon.
This hadith demonstrates the Prophet's mercy in ensuring Muslims do not unnecessarily deprive themselves of permissible sustenance.
Scholarly Insights
Imam Nawawi explained that the vertical light appears about an hour before true dawn and disappears, while the horizontal light remains and intensifies.
Ibn Hajar al-Asqalani noted this hadith contains both a legal ruling and a scientific observation about astronomical phenomena.
The distinction protects Muslims from invalidating their fasts by beginning too early or missing the permissible time for suhur.