Sunan an-Nasa'i 463
سنن النسائي#463Sahihأَخْبَرَنَا الْحُسَيْنُ بْنُ حُرَيْثٍ، قَالَ أَنْبَأَنَا الْفَضْلُ بْنُ مُوسَى، عَنِ الْحُسَيْنِ بْنِ وَاقِدٍ، عَنْ عَبْدِ اللَّهِ بْنِ بُرَيْدَةَ، عَنْ أَبِيهِ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " إِنَّ الْعَهْدَ الَّذِي بَيْنَنَا وَبَيْنَهُمُ الصَّلاَةُ فَمَنْ تَرَكَهَا فَقَدْ كَفَرَ " .
It was narrated from 'Abdullah bin Buraidah that his father said:"The Messenger of Allah (ﷺ) said: 'The covenant that stands between us and them is the Salah; whoever abandons it, he has committed disbelief
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:
In-book reference: 5:16