Is there an elective and a necessary time for Dhuhr and Fajr prayers, or does the time for Dhuhr end with the entry of Asr, and the time for Fajr with the rising of the sun only, and have scholars differed regarding the time of these two prayers?

The time for Fajr prayer begins with the appearance of true dawn and extends until sunrise. The majority of scholars hold that there is no time of necessity for it, but the preferred time for performing it is before isfar (when light spreads). Some scholars, however, are of the view that Fajr has a time of necessity that extends until sunrise, and this time is considered a permissible time for those with excuses.

As for the time for Dhuhr prayer, it begins when the sun passes its zenith (zawal) and extends until the shadow of everything becomes equal to its length. The majority of scholars hold that there is no time of necessity for this prayer.