Sunni Muslims
The time period within which the Isha prayer must be recited is the following:
- Time begins: According to the Hanafi school, Isha begins when complete darkness has arrived and the white twilight in the sky has disappeared. According to the Maliki and Shafi'i schools, the time begins when the red thread has disappeared from the sky. These times can be approximated by using the sun as a measure. When the sun has descended 12 degrees below the horizon, it is approximately equivalent to the disappearance of the red from the sky. For approximating when complete darkness begins, some astronomers argue that it occurs when the sun has descended 15 degrees below the horizon while others use the safer of 18 degrees.
- Time ends: At the beginning of dawn when the time for Fajr prayer begins. However, it is frowned upon (and sinful in the Maliki school) to delay the prayer without a legitimate excuse past the first 1/3 of the night ("night" in Islamic law means the time between the entrance of the Maghrib prayer and the entrance of the Fajr prayer). According to a minority opinion in the Maliki school, the prohibition is from delaying the prayer beyond 1/2 the night, rather than just 1/3.
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