Is delaying the 'Isha prayer until just before its time expires considered procrastination and a sin, and will repentance for that be accepted, especially if the delay goes beyond the designated prayer time with knowledge of this, and is it obligatory to prioritize the fard (obligatory) prayer over the sunnah (supererogatory) prayer if the prayer time is short?

We advise the questioner to fear Allah and to preserve the prayers at their appointed times, for delaying them without a valid Shar’i excuse is among the major sins. She must offer sincere repentance, which erases what preceded it, and its conditions are abandoning the sin, regretting it, and resolving not to return to it.

Regarding making up the Fajr prayer after its time has passed, the preponderant view among the majority of scholars, and upon which our fatwa (definition) is based, is to offer the two rak’ahs of Fajr (Sunnah (definition)) before the obligatory prayer. This is in emulation of the action of the Prophet, peace and blessings be upon him. However, if time is constrained such that it is not sufficient for both the obligatory prayer and the Sunnah together, then one should begin with the obligatory prayer, and then the two rak’ahs of Fajr are prayed afterwards.