Sahih Muslim Book 4, Hadith Number 1191.

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

Abdullah (b. ‘Umar) reported: The Apostle of Allah (may peace be upon him) recited (Surat) al Najm and performed prostration during its recital and all those who were along with him also prostrated themselves except one old man who took a handful of pebbles or dust in his palm and lifted it to his forehead and said: This is sufficient for me. ‘Abdullah said: I saw that he was later killed in a state of unbelief.