Sahih al-Bukhari 4919
Sahih al-Bukhari · Book 65: Prophetic Commentary on the Qur'an (Tafseer of the Prophet (pbuh)) · "(Remember) the Day when the Shin shalt be laid bare..." (V.68:42)
Narrated Abu Sa`id:
حَدَّثَنَا آدَمُ ، حَدَّثَنَا اللَّيْثُ ، عَنْ خَالِدِ بْنِ يَزِيدَ ، عَنْ سَعِيدِ بْنِ أَبِي هِلاَلٍ ، عَنْ زَيْدِ بْنِ أَسْلَمَ ، عَنْ عَطَاءِ بْنِ يَسَارٍ ، عَنْ أَبِي سَعِيدٍ ـ رضى الله عنه ـ قَالَ سَمِعْتُ النَّبِيَّ صلى الله عليه وسلم يَقُولُ " يَكْشِفُ رَبُّنَا عَنْ سَاقِهِ فَيَسْجُدُ لَهُ كُلُّ مُؤْمِنٍ وَمُؤْمِنَةٍ، وَيَبْقَى مَنْ كَانَ يَسْجُدُ فِي الدُّنْيَا رِئَاءً وَسُمْعَةً، فَيَذْهَبُ لِيَسْجُدَ فَيَعُودُ ظَهْرُهُ طَبَقًا وَاحِدًا " .
I heard the Prophet (ﷺ) saying, "Our Lord Allah will lay bare His Shin, and then all the Believers, men and women, will prostrate themselves before Him, but there will remain those who used to prostrate in the world for showing off and for gaining good reputation. Such people will try to prostrate (on the Day of Judgment) but their back swill be as stiff as if it is one bone (a single vertebra).