كتاب الْمَسَاجِدِ وَمَوَاضِعِ الصَّلاَةِ
5  
The Book of Mosques and Places of Prayer
(20)
Chapter: The prostration of recitation
(20)
باب سُجُودِ التِّلاَوَةِ ‏
Sahih Muslim 575 b

Ibn 'Umar reported:

Sometimes the Messenger of Allah (ﷺ) recited the Qur'an, and would pass by (recite) the verse of sajda and performed prostration and he did this along with us, but we were so crowded in his company that none of us could find a place for performing prostration. (and it was done on occasions) other than prayer.
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا مُحَمَّدُ بْنُ بِشْرٍ، حَدَّثَنَا عُبَيْدُ اللَّهِ بْنُ عُمَرَ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، قَالَ رُبَّمَا قَرَأَ رَسُولُ اللَّهِ صلى الله عليه وسلم الْقُرْآنَ فَيَمُرُّ بِالسَّجْدَةِ فَيَسْجُدُ بِنَا حَتَّى ازْدَحَمْنَا عِنْدَهُ حَتَّى مَا يَجِدُ أَحَدُنَا مَكَانًا لِيَسْجُدَ فِيهِ فِي غَيْرِ صَلاَةٍ ‏.‏
Reference : Sahih Muslim 575b
In-book reference : Book 5, Hadith 134
USC-MSA web (English) reference : Book 4, Hadith 1190
  (deprecated numbering scheme)