Sahih MuslimChapter 4Hadith 860
Full Sharh — Sahih Muslim 860
حَدَّثَنَا مُحَمَّدُ بْنُ رَافِعٍ، حَدَّثَنَا عَبْدُ الرَّزَّاقِ، حَدَّثَنَا مَعْمَرٌ، عَنْ هَمَّامِ بْنِ مُنَبِّهٍ، عَنْ أَبِي هُرَيْرَةَ، عَنِ النَّبِيِّ صلى الله عليه وسلم بِمِثْلِهِ غَيْرَ أَنَّهُ قَالَ " حَتَّى يَظَلَّ الرَّجُلُ إِنْ يَدْرِي كَيْفَ صَلَّى " .
English Translation
A hadith like it has been narrated by Abu Huraira but for these words:" He (the man saying the prayer) does not know how much he has prayed
Source
Sahih Muslim(صحيح مسلم)
The Book of Prayers
Hadith Number
860