The Book of Mosques and Places of Prayer
5/39. Chapter:
The time of `Isha and delaying it
Sahih Muslim
وَحَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا وَكِيعٌ، حَدَّثَنَا سُفْيَانُ، عَنْ عَبْدِ اللَّهِ بْنِ أَبِي لَبِيدٍ، عَنْ أَبِي سَلَمَةَ بْنِ عَبْدِ الرَّحْمَنِ، عَنِ ابْنِ عُمَرَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " لاَ تَغْلِبَنَّكُمُ الأَعْرَابُ عَلَى اسْمِ صَلاَتِكُمُ الْعِشَاءِ فَإِنَّهَا فِي كِتَابِ اللَّهِ الْعِشَاءُ وَإِنَّهَا تُعْتِمُ بِحِلاَبِ الإِبِلِ " .
Ibn 'Umar said: The Messenger of Allah (ﷺ) said: Let the bedouin not gain upper band over you In regard to the name of your prayer, i. e. night prayer, for it is mentioned 'Isya' in the Book of Allah (i. e. the Qur'an). (The bedouin call it 'Atama because) they make delay in milling their she-camels.
Reference : Sahih Muslim 644bIn-book reference : Book 5, Hadith 289USC-MSA web (English) reference : Book 4, Hadith 1344