It is narrated from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that the Prophet (peace and blessings be upon him) used to recite the Qur'an. If it was a surah containing a prostration, he would prostrate and we would prostrate with him (peace and blessings be upon him), until some of us could not find a place to put our foreheads.
(b) These are the words of Abu Khaythamah's hadith; the wording of the others' hadith is that the Prophet (peace and blessings be upon him) used to recite the Qur'an to us. Both narrations say: until one of us could not find a place to put his forehead for prostration.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3699