What is the correct practice for one who calls the Adhan before the prescribed time, such as for Fajr?
Chapter on Adhan
Al-Mughni
Book of Prayer
Primary text
The Mu'adhdhin (caller to prayer) who calls the Adhan before the prescribed time must maintain absolute consistency, performing the Adhan at the exact same time throughout all nights. This consistency ensures that the people learn his customary time and rely upon his call to know the actual entry of the time. The benefit of this consistent pre-time Adhan is to inform the community regarding the timing.
Supporting text
It is prohibited to alternate between calling the Adhan before the time on some occasions and calling it exactly at the time on others, as this causes confusion for the people. Such inconsistency might lead some who hear the early call to pray Fajr prematurely, or conversely, cause those fasting (Saa'im) to refrain from their pre-dawn meal (Suhur) or voluntary worship based on the call, only to realize the time had not yet entered. Furthermore, inconsistent timing, even if all calls are early, diminishes the utility of the Adhan if the time cannot be determined due to the variance.