Sunan an-Nasa'i 791
سنن النسائي#791Sahihأَخْبَرَنَا زِيَادُ بْنُ أَيُّوبَ، قَالَ حَدَّثَنَا إِسْمَاعِيلُ، قَالَ حَدَّثَنَا عَبْدُ الْعَزِيزِ، عَنْ أَنَسٍ، قَالَ أُقِيمَتِ الصَّلاَةُ وَرَسُولُ اللَّهِ صلى الله عليه وسلم نَجِيٌّ لِرَجُلٍ فَمَا قَامَ إِلَى الصَّلاَةِ حَتَّى نَامَ الْقَوْمُ .
It was narrated that Anas said:"The Iqamah for prayer was said, and the Messenger of Allah (ﷺ) was conversing privately with a man, and did not commence the prayer until the people slept
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiSahih - Agreed Upon
In-book reference: 10:15