Jami` at-Tirmidhi 2622
جامع الترمذي#2622Sahihحَدَّثَنَا قُتَيْبَةُ، حَدَّثَنَا بِشْرُ بْنُ الْمُفَضَّلِ، عَنِ الْجُرَيْرِيِّ، عَنْ عَبْدِ اللَّهِ بْنِ شَقِيقٍ الْعُقَيْلِيِّ، قَالَ كَانَ أَصْحَابُ مُحَمَّدٍ صلى الله عليه وسلم لاَ يَرَوْنَ شَيْئًا مِنَ الأَعْمَالِ تَرْكُهُ كُفْرٌ غَيْرَ الصَّلاَةِ . قَالَ أَبُو عِيسَى سَمِعْتُ أَبَا مُصْعَبٍ الْمَدَنِيَّ يَقُولُ مَنْ قَالَ الإِيمَانُ قَوْلٌ يُسْتَتَابُ فَإِنْ تَابَ وَإِلاَّ ضُرِبَتْ عُنُقُهُ .
Narrated Abdullah bin Shaqiq Al-'Uqayli:The Companions of Muhammad (ﷺ) didn't consider leaving anything to be disblief except for the Salat
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: 40:17