Sahih Bukhari
Merits of the Helpers in Madinah (Ansaar)
Volume: 005 / Book Number: 058 / Hadith Number: 192
Narrated 'Abdullah:
The Prophet recited Surat An-Najam and prostrated, and there was nobody who did not prostrate then except a man whom I saw taking a handful of pebbles, lifting it, and prostrating on it. He then said, "This is sufficient for me." No doubt I saw him killed as a disbeliever afterwards.