Hadith 132

وعن عائشة رضي الله عنها قالت : أعتم النبي صلى الله عليه وآله وسلم ذات ليلة بالعشاء حتى ذهب عامة الليل ثم خرج فصلى وقال : « إنه لوقتها لولا أن أشق على أمتي » رواه مسلم.
Narrated 'Aishah (RA): The Prophet (ﷺ) delayed (the 'Isha' prayer) one night till a great part of the night passed, then he went out and offered the prayer, and said, "This is the proper time for it; were it not that I would impose a burden on my followers." [Reported by Muslim].
Hadith Reference بلوغ المرام / 132
Hadith Grading محدثین: صحيح
Hadith Takhrij «أخرجه مسلم، المساجد، باب وقت العشاء وتأخيرها، حديث:638.»
Explanation & Benefits
Shaykh Safi ur-Rahman Mubarakpuri
Lexical Explanation:
«أَعتَمْ» means to delay, to be late. It is derived from «إِعْتَام», which means: to enter at the time of darkness.
«اَلْعَتْمَة» refers to the early third (one-third) of the night after the disappearance of twilight, or it refers to absolute darkness after the setting of twilight. And according to one opinion, it is derived from «اَلْعَتْم», which means to delay and to defer.
«عَامَّةُ اللَّيْلِ» means the greater part of the night.
«إِنَّهُ لَوَقْتُهَا» refers to the chosen and most virtuous time.

Benefit:
This hadith is clear evidence that it is more virtuous to perform the ‘Isha prayer with delay. The reward of superiority for performing it with delay is specific only to this prayer and not to any other prayer. It has already been mentioned that the Messenger of Allah (sallallahu alayhi wa sallam) would sometimes wait for the arrival of the worshippers for this prayer; if they gathered late, he would also delay the prayer, and if the worshippers gathered early, he would lead the congregation early. In other words, the Prophet (sallallahu alayhi wa sallam) would take care of his ummah; whatever would cause hardship and difficulty for the individuals of the ummah, he would try to make it easy for them.
Source: Bulugh al-Maram: Commentary by Safiur Rahman Mubarakpuri, Page: 132