The Ruling on Delaying ‘Isha’ Prayer
Q: Some questioner from Riyadh says that some people, when asked why they delay ‘Isha’ (Night) Prayer during work and the like, claim that its time lasts until midnight and there is flexibility in this regard.
I hope you explain the ruling on this question and provide the evidence for it. May Allah protect you and grant you success.
A: Every Muslim has to offer ‘Isha’ and other Prayers in congregation at the due time. It is impermissible to delay it for the sake of work. No one is allowed to miss the congregation except for a Shar’y (Islamically lawful) excuse, such as sickness. The Prophet (صلى الله عليه وسلم) said, “Whoever hears the call (adhaan) and he does not come to it (the prayer), then there is no prayer for him unless he has a [legal] excuse.” When Ibn Abbas was asked what the excuse is, he replied, ‘sickness or fear.’
[Majmoo ‘al-Fataawa Ibn Baaz, Vol. 10; pp. 388 – 389]