He replied:

The prescribed time includes both its beginning and its end, and Allah accepts the prayer throughout that time. However, its beginning is preferable to its end, except where the Lawgiver has made an exception, such as delaying Zuhr in intense heat, or delaying ‘Ishā’ when this causes no hardship to the congregation. And Allah knows best.

He—may Allah have mercy on him—was asked:

Must the night extend until sunrise? And what is the shortest interval between the time of Maghrib and the beginning of ‘Ishā’, measured in lunar mansions?

He replied:

The time for ‘Ishā’ begins when the red twilight disappears. Among buildings, however, one should take the precaution of waiting until the white twilight disappears, since walls may conceal the redness. Once the whiteness has disappeared, one can be certain that the red twilight has gone. This is the position of the majority, including Mālik, al-Shāfi‘ī and Ahmad.

Abū Hanīfa, however, holds that twilight means the whiteness. Astronomical calculators say that its duration is two lunar mansions. But this is not a consistent measure, for the mansions are identified by stars, some of which lie close to the actual mansion, while others lie far from it. Moreover, the interval before ‘Ishā’ varies in length with the day, so it becomes