Full Sharh — Sahih Muslim 1265
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنِ ابْنِ شِهَابٍ، عَنْ أَبِي سَلَمَةَ بْنِ عَبْدِ الرَّحْمَنِ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " إِنَّ أَحَدَكُمْ إِذَا قَامَ يُصَلِّي جَاءَهُ الشَّيْطَانُ فَلَبَسَ عَلَيْهِ حَتَّى لاَ يَدْرِي كَمْ صَلَّى فَإِذَا وَجَدَ ذَلِكَ أَحَدُكُمْ فَلْيَسْجُدْ سَجْدَتَيْنِ وَهُوَ جَالِسٌ " .
English Translation
Abu Huraira reported:The Messenger of Allah (ﷺ) said: When any one of you stands up to pray, the devil comes to him and confuses him to that he does not know how much he has prayed. If any one of you has such an experience he should perform two prostrations while sitting down (in qa'da)
Source
Sahih Muslim(صحيح مسلم)
The Book of Mosques and Places of Prayer
Hadith Number
1265