Sahih Muslim Book 4, Hadith Number 1190.

Chapter : Forgetfulness in prayer and prostration as compensation for it.

Ibn ‘Umar reported: Sometimes the Messenger of Allah (may peace be upon him) 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.