Musnad Ahmad 26:685

Yahya ibn Sa'id narrated to us, from Shu'bah, who said: Abu Ishaq narrated to me, from al-Aswad, from 'Abdullah, that the Prophet (ﷺ) recited [Surah] an-Najm, and he prostrated during it, and those who were with him [prostrated]. Except for an old man who took a handful of pebbles or dirt, and he said: "It is enough for me like this," and he placed it against his forehead. He [the narrator] said: And I indeed saw him killed as a disbeliever.