Question:
What is the ruling on delaying the Isha prayer until a late
hour?
Answer:
It is better for the Isha prayer to be delayed to its later
time. The more it is delayed, the better, unless it be for a man because if a
man delays it, he misses the congregational prayer, and it is not permissible
for him to delay it and miss the congregational prayer. As for the women in their houses, the
more they delay the Isha prayer, the better it is for them, but they should not
delay it past midnight.
Shaykh Muhammad bin Saalih al-`Uthaymeen
Fatawa Islamiyah Vol. 2 Page 239
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Source: http://www.fatwaislam.com/fis/index.cfm?scn=fd&ID=1090
