Until what time is the 'Isha prayer accepted? And is it permissible to pray it before its time out of necessity?

It is not permissible to perform the 'Isha prayer before its prescribed time, except in cases where it is permissible to combine two prayers, either by advancing or delaying them.

The 'Isha prayer has two timeframes: - An optimal time (waqt ikhtiyar): This extends until one-third or half of the night. - A time of necessity (waqt darurah): This is from the end of the optimal time until the true dawn appears. Some scholars hold that one incurs sin by delaying the prayer until this time without a valid excuse. Others, however, view it as a permissible time, and that there is no sin upon one who delays it until then, even if they miss the preferred timing.

The evidence for the 'Isha prayer's time extending until dawn is based on the hadith of Abu Qatadah: "There is no negligence in sleep; rather, negligence is upon one who delays the prayer until the time of the next prayer enters." It is also supported by the fatwa of the Companions to a menstruating woman who purifies herself before dawn, instructing her to pray both Maghrib and 'Isha.