Hadith 5542
وَعَنْهُ قَالَ: سَمِعْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَقُولُ: «يَكْشِفُ رَبُّنَا عَنْ سَاقِهِ فَيَسْجُدُ لَهُ كُلُّ مُؤْمِنٍ وَمُؤْمِنَةٍ وَيَبْقَى مَنْ كَانَ يَسْجُدُ فِي الدُّنْيَا رِيَاءً وَسُمْعَةً فَيَذْهَبُ لِيَسْجُدَ فَيَعُودُ ظَهْرُهُ طَبَقًا وَاحِدًا» . مُتَّفق عَلَيْهِ
He told that he heard God's messenger say, "Our Lord will uncover His leg[*] and every believing man and woman will fall in prostration before Him. Those who prostrated themselves in the world from hypocrisy and show will remain, but when they proceed to prostrate themselves, their backs will become a single piece." *Cf. Quran, 48:42. The reference is either to the beginning of terrors, or to the end of all mystery. (Bukhari and Muslim.)