Shaykh Saalih al-Fawzaan was asked the following question:

Question:

May Allah be good to you Oh possessor of virtue: It is well known that the people pray in these lands and sometimes some Islamic lands pray Isha one and a half hour approximately after Maghrib prayer. However, in our lands, we pray after the passing of half of this duration approximately. So is that allowed? They say that this time is sufficient due to the disappearance of the red twilight. Also, in our land there are two main schools of thought. Along with that they agree in this issue, that is the timing. So our question is: what is the cause for this major differing and is there statements in other schools of thought in regards to determining the duration the twilight remains on the horizon?

Answer:

The Messenger sallahu alayhi wa salam determined the time. The time for Isha is when the red twilight disappears. The twilight is two: the white twilight and the red twilight. If the red twilight disappears then Isha is obligatory. The time for Isha is spacious. What is better is to differ its timing in accordance to the difference of the people. If the people gather in the beginning of the time, then they pray in the beginning of the time. If the people delay it, then they pray it in the first third of the night and that is better. The third of the night is better if it is not difficult. If the Prophet sallahu alayhi wa salam saw the people gather early, he prayed early. If they delayed it, he would delay it. He preferred to delay  it, but he did not want difficulty for his Ummah.

By Allah, the difference in the disappearance of the twilight is a difference depending on the people of the land. There is no one time that the twilight disappears for everyone. For example, the disappearance of the twilight in Sham, etc. The people of a land know it. If the twilight disappears, then pray whereever you are and if the red twilight is present, then do not pray. Yes”

[Reference]

Translated by

Faisal Ibn Abdul Qaadir Ibn Hassan
Abu Sulaymaan

Shaikh Muqbil rahimahullah said:

“As for the time [when isha enters], then it is an issue based on opinion/examination which a Scholar and an ignorant one both share in. So if the twilight leaves, then the time of Isha has entered and perhaps it does not leave except after 45 minutes. As I said, oh my brothers for the sake of Allah, It is an issue based on opinion/examination. It is possible that you leave from the electricity towards the desert to see the twilight leave. Does it leave after 45 mins or 1 hour exactly or less or more? That which is apparent to me is that it leaves after 45 mins…”

[Reference]

Translated by

Faisal Ibn Abdul Qaadir Ibn Hassan
Abu Sulaymaan