Musnad Ahmad 30:2225

'Affan narrated to us, he said: Hammam narrated to us, he said: Yahya ibn Abi Kathir narrated to us, from Abu Salamah, who said: I saw Abu Hurairah recite: "When the sky has split [asunder]" [Al-Inshiqaq: 1], and he prostrated. I said: Did I not see you prostrate? He said: "Had I not seen the Messenger of Allah, peace and blessings of Allah be upon him, prostrate in it, I would not have prostrated."